Servo control method and device for fluorescent optical disc, and data read-write device

Abstract

The invention discloses a servo control method and device of a fluorescent optical disc and a data read-write device, and belongs to the technical field of optical discs. The method comprises the following steps: a servo control unit controls servo light to be focused on a servo surface of a fluorescent optical disc; the light receiver obtains a plurality of first servo error signals based on the servo feedback light and provides the plurality of first servo error signals for the first signal processing unit, and the first servo error signals are used for indicating the distance between the light spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc; the first signal processing unit obtains a second servo error signal based on the plurality of first servo error signals and provides the second servo error signal for the servo control unit, and the second servo error signal is used for indicating the condition that the distance between the light spot position of the servo light on the fluorescent optical disc and the target spot position of the fluorescent optical disc changes along with time; and the servo control unit obtains an adjusted servo control signal based on the second servo error signal. According to the invention, the precision of servo control is improved.

Description

Technical Field

[0001] The present application relates to the technical field of optical discs, and in particular to a servo control method and device for a fluorescent optical disc, and a data reading and writing device. Background Art

[0002] Optical storage media are widely used to store cold data because they have the function of preserving data for a long time, such as fluorescent optical discs. The process of reading and writing data from a fluorescent optical disc is a dynamic process of continuously focusing the laser on the fluorescent optical disc and adjusting the focus position according to the focusing result. This dynamic process requires multiple adjustments to the objective lens, and the process from each adjustment of the objective lens to the next adjustment of the objective lens is called an adjustment process. Each adjustment process includes: the servo control unit controls the objective lens to focus the servo light on the fluorescent optical disc based on the servo control signal, the optical receiver receives the light signal fed back from the fluorescent optical disc, converts the light signal into a servo error signal, and provides the servo error signal to the servo control unit, and the servo control unit obtains a servo control signal based on the servo error signal, so as to adjust the objective lens based on the servo control signal in the next adjustment process, so that the objective lens focuses the servo light on the fluorescent optical disc.

[0003] At present, when processing the signal generated in the servo control process of the fluorescent optical disc, the conventional signal processing method for general optical discs is usually adopted, such as treating the signal generated in the servo control process as a continuous signal for processing.

[0004] However, since the fluorescent optical disc contains discrete signals stored in the form of holes, the servo feedback light triggered by the laser on the fluorescent optical disc exhibits discrete characteristics, and the traditional signal processing method cannot meet the accuracy of servo control. Summary of the invention

[0005] The present application provides a servo control method and device for a fluorescent optical disc, and a data reading and writing device. The present application effectively improves the accuracy of servo control based on servo feedback light fed back by the fluorescent optical disc. The technical solution provided by the present application is as follows:

[0006] In a first aspect, the present application provides a servo control method for a fluorescent optical disc. The method is applied to a servo control device for a fluorescent optical disc. The servo control device for a fluorescent optical disc comprises: a servo control unit, an optical processing unit, a light receiver and a first signal processing unit. The method comprises: the servo control unit controls the optical processing unit based on a servo control signal, so that the servo light is focused on the servo surface of the fluorescent optical disc through the optical processing unit; the light receiver receives the servo feedback light of the fluorescent optical disc to the servo light, obtains a plurality of first servo error signals based on the servo feedback light, and provides a plurality of first servo error signals to the first signal processing unit, the first servo error signal is used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc; the first signal processing unit obtains a second servo error signal based on the plurality of first servo error signals, and provides a second servo error signal to the servo control unit, the second servo error signal is used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc changes with time; the servo control unit obtains an adjusted servo control signal based on the second servo error signal.

[0007] Since the first servo error signal is used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc. The first servo error signal is expressed as a discrete signal. The second servo error signal is used to indicate the change in the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc over time. The second servo error signal is expressed as a continuous signal. Through the processing of the first servo error signal by the first signal processing unit, the first servo error signal is converted into a second servo error signal that is presented as a continuous signal. In this way, in the servo control process, considering that the servo feedback light fed back by the fluorescent optical disc presents a discrete characteristic, the servo feedback light that presents a discrete characteristic can be converted into a second servo error signal that presents a continuous signal through the processing of the optical receiver and the first signal processing unit. There is no need to use the servo light feedback signal as a continuous signal for servo control, which effectively improves the accuracy of servo control based on the servo feedback light fed back by the fluorescent optical disc, and helps to improve the reading and writing characteristics of the fluorescent optical disc.

[0008] In one implementation, the first signal processing unit obtains the second servo error signal based on multiple first servo error signals, including: the first signal processing unit obtains the timing of the multiple first servo error signals; the first signal processing unit predicts the change trend of the voltage value between the generation moments of any two first servo error signals adjacent in timing based on the voltage values ​​of any two first servo error signals adjacent in timing; the first signal processing unit obtains the second servo error signal based on the change trend and the multiple first servo error signals.

[0009] Optionally, the servo control device of the fluorescent optical disc further includes: a second signal processing unit. In this case, the method further includes: the second signal processing unit receives a plurality of first servo error signals provided by the light receiver; the second signal processing unit divides the plurality of first servo error signals into a plurality of signal sets; and the second signal processing unit provides the plurality of signal sets to the first signal processing unit.

[0010] In one implementation, the second signal processing unit divides the plurality of first servo error signals into a plurality of signal sets, including: the second signal processing unit divides the plurality of first servo error signals into a plurality of signal sets based on the distribution of the voltage values ​​of the plurality of first servo error signals. For example, the second signal processing unit may determine the proximity between the voltage values ​​of the plurality of first servo error signals according to the distribution of the voltage values ​​of the plurality of first servo error signals, and divide the plurality of first servo error signals with relatively close voltage values ​​into the same signal set based on the proximity between the voltage values, and divide the plurality of first servo error signals with relatively large voltage value differences into different signal sets. When the voltage values ​​of the plurality of first servo error signals are relatively close, it indicates that the commonality of the contents represented by the plurality of first servo error signals is relatively high, and therefore the plurality of first servo error signals may be divided into the same signal set. When the voltage values ​​of the plurality of first servo error signals are relatively different, it indicates that the differences of the contents represented by the plurality of first servo error signals are relatively large, and therefore the plurality of first servo error signals may be divided into different signal sets.

[0011] Optionally, the servo control device of the fluorescent optical disc further includes: a third signal processing unit. In this case, the method further includes: the third signal processing unit receives multiple signal sets provided by the second signal processing unit; the third signal processing unit obtains a voltage threshold of any signal set based on the voltage value of the first servo error signal in any signal set; the third signal processing unit adjusts the voltage of the first servo error signal in any signal set based on the voltage threshold of any signal set to obtain multiple adjusted signal sets; the third signal processing unit provides the multiple adjusted signal sets to the first signal processing unit.

[0012] By processing the first servo error signal by the second signal processing unit and the third signal processing unit, the accuracy of the first servo error signal can be improved, which helps to improve the accuracy of servo control based on the first servo error signal.

[0013] In one implementation, the third signal processing unit obtains the voltage threshold of any signal set based on the voltage value of the first servo error signal in any signal set, including: the third signal processing unit obtains the voltage coverage range of the first servo error signal in any signal set based on the voltage value of the first servo error signal in any signal set; the third signal processing unit determines the voltage threshold of any signal set based on the voltage coverage range of any signal set.

[0014] For example, for any signal set, multiple first servo error signals in the signal set are relatively close, and the contents they represent are likely to be the same, so after obtaining the voltage threshold of the signal set, the voltage values ​​of all first servo error signals in the signal set can be adjusted to be equal to the voltage threshold of the signal set, so that the adjusted multiple first servo error signals can represent the same content. That is, the voltage of the adjusted first servo error signal is equal to the voltage threshold of the signal set to which the first servo error signal belongs.

[0015] In a second aspect, the present application provides a servo control device for a fluorescent optical disc. The device includes: a servo control unit, an optical processing unit, a light receiver, and a first signal processing unit. The servo control unit is used to control the optical processing unit based on a servo control signal, so that the servo light is focused on the servo surface of the fluorescent optical disc through the optical processing unit; the light receiver is used to receive the servo feedback light of the fluorescent optical disc to the servo light, obtain a plurality of first servo error signals based on the servo feedback light, and provide a plurality of first servo error signals to the first signal processing unit, the first servo error signal is used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc; the first signal processing unit is used to obtain a second servo error signal based on the plurality of first servo error signals, and provide a second servo error signal to the servo control unit, the second servo error signal is used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc changes over time; the servo control unit is also used to obtain an adjusted servo control signal based on the second servo error signal.

[0016] Optionally, the first signal processing unit is specifically used to: obtain the timing of multiple first servo error signals; predict the changing trend of the voltage value between the generation moments of any two first servo error signals adjacent in timing based on the voltage values ​​of any two first servo error signals adjacent in timing; and obtain the second servo error signal based on the changing trend and multiple first servo error signals.

[0017] Optionally, the device further comprises: a second signal processing unit. The second signal processing unit is configured to: receive a plurality of first servo error signals provided by the optical receiver; divide the plurality of first servo error signals into a plurality of signal sets; and provide the plurality of signal sets to the first signal processing unit.

[0018] Optionally, the second signal processing unit is specifically configured to: divide the plurality of first servo error signals into a plurality of signal sets based on distribution of voltage values ​​of the plurality of first servo error signals.

[0019] Optionally, the device further includes: a third signal processing unit. The third signal processing unit is used to: receive multiple signal sets provided by the second signal processing unit; obtain a voltage threshold of any signal set based on the voltage value of the first servo error signal in any signal set; adjust the voltage of the first servo error signal in any signal set based on the voltage threshold of any signal set to obtain multiple adjusted signal sets; and provide the multiple adjusted signal sets to the first signal processing unit.

[0020] Optionally, the third signal processing unit is specifically used to: obtain a voltage coverage range of the first servo error signal in any signal set based on the voltage value of the first servo error signal in any signal set; and determine a voltage threshold of any signal set based on the voltage coverage range of any signal set.

[0021] Optionally, the voltage of the adjusted first servo error signal is equal to a voltage threshold of a signal set to which the first servo error signal belongs.

[0022] Optionally, the light receiving unit is a photomultiplier tube.

[0023] In a third aspect, the present application provides a data reading and writing device for a fluorescent optical disc, the data reading and writing device comprising the servo control device provided in the first aspect of the present application and any possible implementation thereof. By way of example, the data reading and writing device comprises a processor, the processor being used to execute program code, so that the data reading and writing device executes the method provided in the first aspect of the present application and any possible implementation thereof.

[0024] In a fourth aspect, the present application provides a computer program product comprising instructions, which, when executed by a data reading and writing device, enables the data reading and writing device to execute the method provided in the first aspect of the present application and any possible implementation thereof.

[0025] In a fifth aspect, the present application provides a computer-readable storage medium, which is a non-volatile computer-readable storage medium, and the computer-readable storage medium includes computer program instructions. When the computer program instructions are executed by a data reading and writing device, the data reading and writing device executes the method provided in the first aspect of the present application and any possible implementation thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a cross-sectional schematic diagram of a fluorescent optical disc provided in an embodiment of the present application;

[0027] Figure 2 It is a schematic diagram of the arrangement of tracks of a fluorescent optical disc provided in an embodiment of the present application;

[0028] Figure 3 It is a partial schematic diagram of a guide layer of a fluorescent optical disc provided in an embodiment of the present application;

[0029] Figure 4 is a schematic diagram of a servo control device for a fluorescent optical disc provided in an embodiment of the present application;

[0030] Figure 5 is a schematic diagram of another servo control device for a fluorescent optical disk provided in an embodiment of the present application;

[0031] Figure 6 is a structural schematic diagram of an optical processing unit provided in an embodiment of the present application;

[0032] Figure 7 is a flow chart of a servo control method for a fluorescent optical disc provided in an embodiment of the present application;

[0033] Figure 8 is a schematic diagram of a plurality of first servo error signals provided by an embodiment of the present application;

[0034] Fig. 9 is a schematic diagram of a plurality of first servo error signals after removing noise points provided by an embodiment of the present application;

[0035] Fig.10 is a schematic diagram of a first servo error signal that is not adjusted according to a voltage threshold value provided by an embodiment of the present application;

[0036] Fig.11 is a schematic diagram of a first servo error signal adjusted according to a voltage threshold provided by an embodiment of the present application;

[0037] Fig.12 It is a schematic diagram of the structure of an LSTM neural network provided in an embodiment of the present application;

[0038] Fig.13 is a schematic diagram of the structure of a lead-lag controller provided in an embodiment of the present application;

[0039] Fig.14 is a schematic diagram of the structure of another lead-lag controller provided in an embodiment of the present application;

[0040] Fig.15 It is a structural diagram of a fuzzy adaptive PID controller provided in an embodiment of the present application;

[0041] Fig.16 It is a structural schematic diagram of a data reading and writing device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0043] The present application relates to a servo control device for a fluorescent optical disc. The servo control device for a fluorescent optical disc is used to read data and / or write data (i.e., read and write data) on the fluorescent optical disc. The fluorescent optical disc is mounted on the servo control device for the fluorescent optical disc. A fluorescent optical disc refers to a recording medium that records and reads data by laser irradiation. In the embodiments of the present application, although the fluorescent optical disc is used as an example for illustration, the present application is also applicable to other optical storage media that have similar characteristics as the fluorescent optical disc in the way of reading and writing data, and the present application does not list them one by one.

[0044] For example, Figure 1 is a cross-sectional schematic diagram of a fluorescent optical disc provided in an embodiment of the present application. Figure 1 As shown, the fluorescent optical disc 100 includes a protective layer 11, s information layers 12, a reflective layer 13 and a guide layer 14 arranged in sequence. Where s is an integer greater than or equal to 1, and the embodiment of the present application does not limit the value of s. The functions of each layer in the fluorescent optical disc 100 are as follows:

[0045] The protection layer 11 is used to protect each information layer 12 so that the fluorescent optical disc 100 can withstand frequent use, fingerprints, scratches and dirt, etc., and ensure the security of the data stored in the fluorescent optical disc 100.

[0046] In the case of multiple information layers 12, in order to distinguish each information layer 12, each information layer 12 is numbered L1 to Ls in sequence according to the distance from the guide layer 14. Among them, L1 is the information layer 12 closest to the guide layer 14, and Ls is the information layer 12 farthest from the guide layer 14.

[0047] The information layer 12 is used to record data. The way of recording data is: when the laser irradiates the information layer 12, the medium constituting the surface of the information layer 12 will undergo physical or chemical changes, changing the state of the medium, and the recorded data is represented by the state of the medium. Taking the medium as a phase change material as an example, when the laser irradiates the information layer 12, the laser causes the state of part of the material in the phase change material to change from an amorphous state to a crystalline state. The phase change material in the crystalline state can represent a type of data, such as representing data "1". The area where the phase change material is not distributed in the information layer 12 can represent another type of data, such as representing data "0". Of course, the phase change material in the crystalline state can also represent data "0", and the area where the phase change material is not distributed in the information layer 12 can represent data "1". Alternatively, when the laser irradiates the information layer 12, the laser can cause the state of part of the material in the phase change material to change from an amorphous state to a crystalline state, and according to different written data, the crystalline state can be divided into multiple excited states, and different excited states are used to represent different written data. For example, when the written data is different, the area size of the part of the phase change material that is converted into a crystalline state is different, and different sizes represent different written values.

[0048] Exemplarily, the information layer 12 includes a land in area and a data area. The land in area is used to store metadata of the fluorescent optical disc, and the metadata includes parameters related to each layer of the fluorescent optical disc 100. The data area is used to record data, and the data area includes a track. Figure 2 As shown, the tracks are arranged in the form of Archimedean spirals from the inside to the outside in the information layer 12. The servo control device of the fluorescent optical disk can record data (i.e. write data) along the tracks in the information layer 12 by irradiating laser light to the tracks, so that the data is arranged in the form of tracks in the information layer 12.

[0049] The reflective layer 13 is disposed between the guide layer 14 and the information layer L1. The reflective layer 13 has the function of reflecting the read / write light and transmitting the servo light. When the read / write light is irradiated to the reflective layer 13, the reflective layer 13 reflects the read / write light to prevent the read / write light from irradiating to the guide layer 14. When the servo light is irradiated to the reflective layer 13, the reflective layer 13 transmits the servo light so that the servo light is irradiated to the guide track 141 of the guide layer 14 to guide the read / write light to read and write data on the information layer 12. In this way, the reflective layer 13 can allow the servo light to penetrate the s information layers 12 and irradiate to the guide layer 14, and prevent the read / write light from irradiating to the guide layer 14.

[0050] Figure 3 FIG. 1 is a partial schematic diagram of a guide layer 14 provided in an embodiment of the present application. Figure 3 As shown, the guide layer 14 includes grooves (also called pits) and blank areas (also called lands) between two adjacent grooves. The pits and the lands appear alternately, forming a track arranged in the form of an Archimedean spiral from the inside to the outside. Please refer to the schematic diagram of the track Figure 1 The track is called a guide track 141 or a guide groove. The guide track 141 is a position guide for recording the read and write positions. The guide track 141 is arranged in the same manner as the track in the information layer 12. Since the guide track 141 is arranged in the same manner as the track in the information layer 11, Figure 1As shown, two laser beams are irradiated to the storage medium through objective lenses respectively, wherein one laser beam is irradiated to the guide track 141 to guide the other laser to read and write data on the track corresponding to the information layer L1. In order to distinguish the two lasers, the laser that guides reading and writing is called servo light, and the laser used for reading and writing data is called read-write light. Moreover, in the embodiment of the present application, the positions of the objective lens for focusing the servo light and the objective lens for focusing the read-write light are fixed. When the fluorescent optical disc 100 has multiple information layers 12, in the process of reading and writing data on the information layer L1, the servo light is irradiated on the guide layer 14, and in the process of reading and writing data on the information layer Li among the information layers L2 to Ls, the servo light is irradiated on the information layer Li-1, that is, the information layer Li-1 is used as a guide layer when reading and writing data on the information layer Li. It can be seen from this that the information layers L1 to Ls-1 and the guide layer 14 can all play a guiding role. The guiding function of the information layers L1 to Ls-1 and the guide layer 14 mainly depends on the servo light irradiating the surface of the layer having the guiding function, so the surface is also called the reference surface (Ref) or the servo surface. For the convenience of description below, the surface of the information layer multiplexed as the guide layer and the surface of the guide layer 14 are collectively referred to as the servo surface.

[0051] Next, combine Figure 4 The principle of reading and writing data on the fluorescent optical disc by the servo control device of the fluorescent optical disc is introduced as follows:

[0052] Figure 4 Schematic diagram of a servo control device for a fluorescent optical disc provided in an embodiment of the present application. Figure 4As shown, the servo control device 200 of the fluorescent optical disc includes a servo control unit 21, an optical processing unit (OPU) 22, a rotating table 23 and a signal processing unit 24. The rotating table 23 is used to mount the fluorescent optical disc 100. The rotating table 23 rotates under the control of the servo control unit 21, so that the fluorescent optical disc 100 rotates with the rotating table 23. The servo control unit 21 is also used to control the optical processing unit 22, for example, to adjust the position of the objective lens so that the objective lens focuses the laser on the fluorescent optical disc 100. After the laser is irradiated on the fluorescent optical disc 100, the fluorescent optical disc 100 will emit a servo feedback light for the servo light. The signal processing unit 24 is used to receive the servo feedback light of the fluorescent optical disc 100, convert the servo feedback light into a servo error signal, and provide the servo error signal to the servo control unit 21. The servo control unit 21 is also used to adjust the servo control signal for controlling the optical processing unit 22 based on the servo error signal, and adjust the position of the objective lens through the servo control signal so that the objective lens focuses the laser on the fluorescent optical disc 100 more accurately. When the servo light is focused on the servo surface, the read / write light can be focused on the information layer Lh under the guidance of the servo light, and the information layer Lh will emit read / write feedback light for the read / write light, and data can be read and written on the information layer Lh based on the read / write feedback light. The information layer Lh is the hth information layer 12 in the fluorescent optical disc 100, and h is greater than or equal to 1 and less than or equal to s.

[0053] In one implementation, Figure 5 As shown, the signal processing unit 24 may include an optical receiver 241 and a first signal processing unit 242. Optionally, as Figure 5 As shown, the signal processing unit 24 may further include a second signal processing unit 243 and a third signal processing unit 244. By way of example, the light receiver may be a photomultiplier tube (PMT). When the light receiver is a photomultiplier tube, since the photomultiplier tube can obtain an electrical signal reflecting the light intensity according to the light intensity of the light signal, and can obtain a servo error signal based on a unipolar light signal, the cost of the photomultiplier tube is low, thereby reducing the cost of the servo control device of the fluorescent optical disc.

[0054] Figure 6 Schematic diagram of the structure of an optical processing unit provided in an embodiment of the present application. Figure 6As shown, the optical processing unit 22 is provided with a read / write optical path and a servo optical path. The read / write optical path is used to emit read / write light to the fluorescent optical disc 100 and transmit read / write feedback light. The read / write light includes read light and write light, both of which are lasers irradiated to the fluorescent optical disc 100. The write light is used to write data to the fluorescent optical disc 100. The read light is used to read data from the fluorescent optical disc 100. The read / write feedback light is the feedback light of the fluorescent optical disc 100 to the read / write light. The read / write feedback light includes read feedback light and write feedback light. The read feedback light is the feedback light of the fluorescent optical disc 100 to the read light, and the reading process can be realized by processing the read feedback light. The write feedback light is the feedback light of the fluorescent optical disc 100 to the write light. When the fluorescent optical disc 100 relies on the laser to change the medium on the surface of the information layer 12 to write data, the write feedback light is the fluorescence generated by the medium on the surface of the information layer 12 being excited by the write light. Similarly, the read feedback light is the fluorescence generated by the medium on the surface of the information layer 12 being excited by the read light. The servo optical path is used to emit servo light to the fluorescent optical disc 100 and transmit servo feedback light. The servo feedback light is the feedback light of the fluorescent optical disc 100 to the servo light. The servo control device of the fluorescent optical disc realizes the servo control process by processing the servo feedback light. In the embodiment of the present application, when the information layer Li-1 is reused as a guide layer when reading and writing data on the information layer Li, the servo feedback light is the fluorescence generated by the medium on the surface of the information layer Li-1 being excited by the servo light. Unlike the information layer 12, the guide layer 14 relies on the guide track 141 formed by the pits and banks to achieve the guiding function. At this time, the servo feedback light is the fluorescence reflected by the pits and banks in the guide layer 14 to the servo light.

[0055] The optical transmission process of the read-write light and the servo light on their respective optical paths is introduced below.

[0056] The servo control unit 21 controls the laser emitter a1 to emit laser light to the collimator a2. The collimator a2 converts the divergent laser light into parallel light and provides the parallel light to the shaping prism a3. The shaping prism a3 converts the parallel light that appears as an elliptical spot into parallel light that appears as a circular spot and provides the parallel light that appears as a circular spot to the spectroscope a4. The spectroscope a4 divides the parallel light that appears as a circular spot into a read-write light and a servo light, and provides the read-write light to the polarization spectroscope a51 on the read-write light path and provides the servo light to the polarization spectroscope a52 on the servo light path.

[0057] The polarization beam splitter a51 transmits the incident reading light to the objective lens (OB) a61 on the reading and writing light path. Based on the servo control of the servo control unit, the objective lens a61 focuses the reading light on the information layer 12 of the fluorescent optical disc 100, and forms a light spot of the reading and writing light on the information layer 12. The information layer 12 is excited by the reading and writing light to generate reading and writing feedback light. After the reading and writing feedback light is reflected to the objective lens a61, it is transmitted to the polarization beam splitter a51 through the objective lens a61. The polarization beam splitter a51 reflects the reading and writing feedback light in the direction of the light receiver a71. The light receiver a71 detects the reading and writing feedback light to obtain a light sensing signal of the reading and writing light. The light sensing signal carries the position information of the light spot of the reading and writing light to indicate the irradiation position of the reading and writing light on the information layer 12. Among them, in order to facilitate the distinction between the reading and writing light and the reading and writing feedback light, Figure 6 The read-write light and the read-write feedback light are illustrated separately, and are not used to limit the positions of the read-write light and the read-write feedback light. The positions of the read-write light and the read-write feedback light may overlap or may not overlap, and the embodiments of the present application do not specifically limit them.

[0058] The polarization beam splitter a52 transmits the incident servo light to the objective lens a62 on the servo light path. Based on the servo control of the servo control unit, the objective lens a62 focuses the servo light on the servo surface of the fluorescent optical disc 100, forming a light spot of the servo light on the servo surface. The servo surface generates servo feedback light based on the servo light. After the servo feedback light is reflected to the objective lens a62, it is transmitted to the polarization beam splitter a52 through the objective lens a62. The polarization beam splitter a52 reflects the servo feedback light in the direction of the light receiver a72. The light receiver a72 detects the servo feedback light to obtain a light sensing signal of the servo light. The light sensing signal carries the position information of the light spot of the servo light to indicate the irradiation position of the servo light on the servo surface. In order to facilitate the distinction between the servo light and the servo feedback light, Figure 6 The servo light and the servo feedback light are shown separately, and are not used to limit the positions of the servo light and the servo feedback light. The positions of the servo light and the servo feedback light may overlap or may not overlap, and the embodiments of the present application do not make specific limitations on them.

[0059] Optionally, the light transmitted by the polarization beam splitter may also need to pass through a movable compensating lens (MCL) to adjust the focal length of the light. When the light needs to be irradiated to the objective lens by changing the light path, the light path can be changed by a right-angle prism (RAP), such as Figure 6 In addition, the light may need to pass through a quarter-wave plate (QWA) before entering the objective lens, so that when the light passes through vertically, the phase difference between the ordinary light and the extraordinary light emitted is controlled to 1 / 4 wavelength.

[0060] Wherein, the polarization beam splitter a51 and the polarization beam splitter a52 can be polarization beam splitter prisms (PBS), which are used to transmit or reflect the incident light according to the polarization direction of the incident light. The laser emitter a1 can be a laser diode (LD). In some embodiments, the laser emitter a1 can also be replaced by a laser emitter array, so that the laser emitter array can emit a write light array or a read light array, so that multiple data can be written to the fluorescent optical disc 100 or multiple data can be read at one time, thereby increasing the data reading and writing efficiency of the fluorescent optical disc. The write light array includes multiple write lights, and the read light array includes multiple read lights.

[0061] Above Figure 6 The example is shown by taking the reading and writing optical path and the servo optical path sharing some photoelectric components, for example, the reading and writing optical path and the servo optical path share the laser emitter a1, collimator a2, shaping prism a3 and beam splitter a4, and the reading and writing light and the servo light are coaxial. In other embodiments, the reading and writing optical path and the servo optical path may also use separate optical paths respectively, without sharing photoelectric components.

[0062] The process of reading and writing data from the fluorescent optical disc is a dynamic process of continuously focusing the laser on the fluorescent optical disc 100 and adjusting the focus position according to the focusing result. This dynamic process requires multiple adjustments of the objective lens, and the process from each adjustment of the objective lens to the next adjustment of the objective lens is called an adjustment process. Each adjustment process includes: the servo control unit controls the objective lens to focus the servo light on the fluorescent optical disc 100 based on the servo control signal, the light receiver receives the light signal fed back by the fluorescent optical disc 100, converts the light signal into a servo error signal presented as a discrete signal, and provides the servo error signal to the signal processing unit, the signal processing unit converts the servo error signal presented as a discrete signal into a servo error signal presented as a continuous signal, and provides the servo error signal to the servo control unit, the servo control unit obtains a servo control signal based on the servo error signal, so as to adjust the objective lens based on the servo control signal in the next adjustment process, so that the objective lens focuses the servo light on the fluorescent optical disc 100. The process of the servo control unit performing focusing servo control on the objective lens based on the servo control signal may be as follows: the servo control unit 21 controls the torquer to move the objective lens c2 in the servo direction of the fluorescent optical disc 100 based on the servo control signal, so that the servo light can be irradiated onto the servo surface.

[0063] Since writing data to the fluorescent optical disc 100 relies on laser to change the medium on the surface of the information layer 12, it can be known that the fluorescent optical disc 100 presents multiple independent information points. In addition, the fluorescent optical disc 100 is constantly rotating during the reading and writing process. In each adjustment process, the reading and writing light will scan multiple information points located at different positions. Therefore, the electrical signals corresponding to the reading and writing feedback light of these information points stimulated by the laser are presented as discrete signals. Correspondingly, the servo light will scan multiple target positions. The ideal state of the servo light is to irradiate the center position of the track in the servo surface, and the target position is the center position. Therefore, the servo feedback light generated in each adjustment process includes multiple feedback light beams fed back by multiple target positions. Correspondingly. The servo error signal converted by the optical receiver is actually a plurality of discrete signals corresponding to the multiple feedback light beams. It can be known that the servo error signal presented as a discrete signal is used to reflect the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc. However, the signal that the servo control unit can process is a continuous signal, so a signal processing unit is required to convert the discrete signal into a continuous signal.

[0064] In addition, the guiding effect of the servo light on the read / write light is achieved through the two processes of focusing and tracking. Focusing is the process of adjusting the read / write light to focus on the surface of the information layer. Tracking is the process of adjusting the read / write light to irradiate the center of the track of the information layer. In the servo process of the servo light guiding the read / write light, the read / write light is usually focused on the surface of the information layer through the focusing process, and then the read / write light is adjusted to irradiate the center of the track of the information layer, that is, the focusing process is performed first, and then the tracking process is performed. The focusing process and the tracking process are both processes of adjusting the laser with an inaccurate focus position to an accurate position. Error signals will be generated in both processes, and the next adjustment will be guided by the error signal during the adjustment process. The error signal generated in the focusing process is called a focus error signal (FE), which is used to indicate the distance between the spot position of the servo light and the servo surface. The error signal generated in the tracking process is called a tracking error signal (TE), which is used to indicate the distance between the spot position of the servo light and the track center of the servo surface. Since the servo control method for a fluorescent optical disk provided in the present application can be used for both a focusing process and a tracking process, for ease of description, the focusing error signal and the tracking error signal are collectively referred to as a servo error signal herein.

[0065] According to the above description, the process of reading and writing data from a fluorescent optical disc is a dynamic process including multiple adjustment processes. The following takes the processing of servo feedback light generated in an adjustment process as an example to illustrate the implementation process of the servo control method for a fluorescent optical disc provided in the embodiment of the present application. Figure 7 As shown, the servo control method of the fluorescent optical disc includes the following steps:

[0066] Step 701: The servo control unit controls the optical processing unit based on the initial servo control signal, so that the servo light is focused on the servo surface of the fluorescent optical disk through the objective lens in the optical processing unit.

[0067] In each adjustment process, the servo control signal corresponding to the process can be used to control the objective lens so that the servo light is focused on the servo surface of the fluorescent optical disc through the objective lens. It should be noted that in the adjustment process, the servo light may be accurately irradiated on the servo surface, or may not be irradiated on the servo surface. Here, "the servo light is focused on the servo surface of the fluorescent optical disc through the objective lens in the optical processing unit" means that the control target of the servo control unit is to irradiate the servo light on the servo surface through the objective lens.

[0068] Step 702: The optical receiver receives servo feedback light of the fluorescent optical disc to the servo light, obtains multiple first servo error signals based on the servo feedback light, and provides multiple first servo error signals to the second signal processing unit, wherein the first servo error signals are used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc.

[0069] After the servo light is irradiated on the fluorescent optical disc, the fluorescent optical disc will feedback the servo light, and the optical receiver will receive the servo feedback light fed back by the fluorescent optical disc. According to the previous description, the servo feedback light generated in each adjustment process includes multiple feedback light beams fed back by multiple target positions, so the first servo error signal is actually a plurality of discrete signals corresponding to the multiple feedback light beams, and each first servo error signal is a discrete signal. The first servo error signal can be expressed as x(n), where n indicates the target position providing the feedback light beam, and the first servo error signal x(i) represents the distance between the spot position of the servo light in the current adjustment process and the i-th target position scanned in the current adjustment process.

[0070] The optical receiver can obtain a corresponding first servo error signal based on the light intensity of the feedback light beam, and provide the first servo error signal to the second signal processing unit. The first servo error signal is actually an electrical signal, and the voltage value of the electrical signal represents the light intensity of the feedback light beam. In the focusing process, the first servo error signal is a focusing error signal, and its voltage value indicates the size of the focus of the servo light deviating from the surface of the servo surface. The smaller the voltage value of the focusing error signal, the less the focus of the servo light deviates from the surface of the servo surface, and the more accurately the servo light beam is focused. In an ideal case, when the servo light beam is focused on the surface of the servo surface, the voltage value of the focusing error signal is zero. In the tracking process, the first servo error signal is a tracking error signal, and its voltage value indicates the size of the focus of the servo light deviating from the center position of the track of the servo surface. The smaller the voltage value of the tracking error signal, the less the focus of the servo light deviates from the center position of the track of the servo surface, and the more accurately the servo light beam is tracked. In an ideal case, when the servo light beam tracks at the center position of the track of the servo surface, the voltage value of the tracking error signal is zero.

[0071] In one implementation, the optical receiver has multiple independent receiving areas, and the optical receiver can obtain the first servo error signal based on the light intensity of the feedback light beams received by the multiple receiving areas. For example, the optical receiver has multiple independent receiving areas, and after receiving the feedback light beam, the optical receiver can respectively obtain the light intensity of the feedback light beams received by the multiple receiving areas, obtain the voltage value of the focus error signal by the astigmatism method, and obtain the voltage value of the tracking error signal by the push-pull method.

[0072] Step 703: The second signal processing unit divides the plurality of first servo error signals into a plurality of signal sets based on the voltage values ​​of the plurality of first servo error signals, and provides the plurality of signal sets to the third signal processing unit.

[0073] After receiving the plurality of first servo error signals, the second signal processing unit divides the plurality of first servo error signals into a plurality of signal sets, and then provides the plurality of signal sets to the third signal processing unit, so that the third signal processing unit processes the first servo error signals based on the plurality of signal sets.

[0074] In one implementation, the second signal processing unit may perform feature analysis based on the voltage values ​​of the plurality of first servo error signals, and then divide the plurality of first servo error signals into a plurality of signal sets based on the distribution of the voltage values ​​of the plurality of first servo error signals. For example, the second signal processing unit may determine the proximity between the voltage values ​​of the plurality of first servo error signals based on the distribution of the voltage values ​​of the plurality of first servo error signals, and divide the plurality of first servo error signals with relatively close voltage values ​​into the same signal set based on the proximity between the voltage values, and divide the plurality of first servo error signals with relatively large voltage value differences into different signal sets. When the voltage values ​​of the plurality of first servo error signals are relatively close, it indicates that the commonality of the contents represented by the plurality of first servo error signals is relatively high, and therefore the plurality of first servo error signals may be divided into the same signal set. When the voltage values ​​of the plurality of first servo error signals differ greatly, it indicates that the differences of the contents represented by the plurality of first servo error signals are relatively large, and therefore the plurality of first servo error signals may be divided into different signal sets. The implementation method for determining the proximity of the voltage values ​​of the first servo error signals may be determined according to application requirements. For example, when judging whether two first servo error signals are close, the difference between the voltage values ​​of the two first servo error signals can be obtained. When the difference between the voltage values ​​is less than the difference threshold, it is determined that the voltage values ​​of the two first servo error signals are close. When the difference between the voltage values ​​is greater than or equal to the difference threshold, it is determined that the voltage values ​​of the two first servo error signals are greatly different. In addition, different difference thresholds can be used to measure the closeness of the voltage values ​​and the large difference in the voltage values. For example, when the difference between the voltage values ​​is less than the first difference threshold, it is determined that the voltage values ​​of the two first servo error signals are close. When the difference between the voltage values ​​is greater than or equal to the second difference threshold, it is determined that the voltage values ​​of the two first servo error signals are greatly different. In addition, the difference threshold used to measure the closeness of the voltage values ​​and the large difference in the voltage values ​​can be pre-set, or it can be determined by analyzing multiple first servo error signals and based on the distribution of the voltage values ​​of multiple first servo error signals. The embodiment of the present application does not specifically limit it. In addition, when dividing the plurality of first servo error signals into a plurality of signal sets, it is also necessary to ensure that every two first servo error signals in the same signal set are relatively close, and the voltage values ​​of the first servo error signals in different signal sets differ greatly.

[0075] It should be noted that the process of dividing the signal set can be a multi-round iterative process. For example, in the division process, a difference threshold value can be first determined among the voltage values ​​of the plurality of first servo error signals, and the plurality of first servo error signals can be divided into two signal sets based on the difference threshold value, and then the difference threshold values ​​corresponding to the two signal sets can be determined respectively based on the voltage values ​​of the first servo error signals in the two signal sets, and then the two signal sets can be subdivided according to the difference threshold values ​​corresponding to each signal set, and so on, so as to obtain a plurality of signal sets. Similarly, when different difference threshold values ​​are used to measure the closeness of the voltage values ​​and the large difference in the voltage values, the first difference threshold value and the second difference threshold value can be first determined, and the plurality of first servo error signals can be divided into two signal sets based on the first difference threshold value and the second difference threshold value, and then the difference threshold values ​​corresponding to the two signal sets can be determined respectively based on the voltage values ​​of the first servo error signals in the two signal sets, and then the two signal sets can be subdivided according to the difference threshold values ​​corresponding to each signal set, and so on, so as to obtain a plurality of signal sets.

[0076] In one achievable manner, step 703 may be implemented by a back propagation (BP) neural network. For example, multiple first servo error signals may be represented by an image, and the image may be input into a BP neural network, so that the BP neural network performs feature analysis on the voltage values ​​of the multiple first servo error signals, and divides the multiple first servo error signals into multiple signal sets based on the feature. The BP neural network may be obtained by pre-training using a training set. The result of the pre-training may indicate multiple voltage ranges, and when executing step 703, the multiple first servo error signals may be divided into multiple signal sets based on the multiple voltage ranges. For example, when executing step 703, the multiple voltage ranges obtained by pre-training may be fine-tuned based on the analysis result of the multiple first servo error signals, and when the voltage value of the first servo error signal meets a certain voltage range obtained by fine-tuning, the first servo error signal is divided into the signal set corresponding to the voltage range, thereby dividing the multiple first servo error signals into multiple signal sets.

[0077] Among them, the pre-trained BP neural network can obtain multiple voltage ranges, which are used to indicate the real feedback light of the fluorescent optical disc to the servo light. When using the pre-trained BP neural network to perform feature analysis on multiple first servo error signals, the BP neural network can also filter out the first servo error signals whose voltage values ​​do not match the multiple voltage ranges based on the multiple voltage ranges, so as to remove the noise points in the multiple first servo error signals, and remove the pulse misjudgments caused by spikes or depressions. Then, the signal set is divided based on the multiple first servo error signals after removing the noise points and pulse misjudgments, so as to ensure that the first servo error signals after signal processing can truly reflect the servo error, and improve the accuracy of servo control based on the first servo error signal. In one implementation, the BP neural network can filter out the first servo error signal whose voltage value does not fall into the multiple voltage ranges, or filter out the first servo error signal whose voltage value is a specified multiple of the maximum voltage value and the minimum voltage value in the multiple voltage ranges. Figure 8 As shown, Figure 8 The size of the dot in the middle represents the voltage value of the corresponding first servo error signal. According to the multiple voltage ranges of the BP neural network, it can be obtained that the voltage value of the dot represented by the dotted circle is significantly different from the voltage values ​​of other dots. The dot represented by the dotted circle can be determined as a noise point. The multiple first servo error signals after removing the noise points are as follows: Fig. 9 shown.

[0078] Step 704: The third signal processing unit obtains voltage thresholds of multiple signal sets based on the voltage value of the first servo error signal in the multiple signal sets, adjusts the voltage of the first servo error signal in any signal set based on the voltage threshold of the signal set, and provides the adjusted multiple signal sets to the first signal processing unit.

[0079] After the third signal processing unit receives the multiple signal sets provided by the second signal processing unit, it can obtain the voltage threshold of the signal set based on the voltage value of the first servo error signal in any signal set of the multiple signal sets, and then adjust the voltage value of the first servo error signal in the signal set based on the voltage threshold of the signal set. For example, for any signal set, the multiple first servo error signals in the signal set are relatively close, and the contents they represent are likely to be the same. Therefore, after obtaining the voltage threshold of the signal set, the voltage values ​​of all the first servo error signals in the signal set can be adjusted to be equal to the voltage threshold of the signal set, so that the adjusted multiple first servo error signals can represent the same content. That is, the voltage of the adjusted first servo error signal is equal to the voltage threshold of the signal set to which the first servo error signal belongs. By way of example, assume Fig.10The two arcs in the figure represent two first servo error signals respectively, and the voltage threshold of the signal set of the first servo error signal on the left is V1, and the voltage threshold of the signal set of the first servo error signal on the right is V0. Then, the amplitude of the first servo error signal on the left can be reduced so that its voltage value is equal to V1, and the amplitude of the first servo error signal on the right can be reduced so that its voltage value is equal to V0. The waveforms of the two adjusted first servo error signals are as follows: Fig.11 shown.

[0080] In one implementation, the third signal processing unit can count the voltage values ​​of the first servo error signals in multiple signal sets, obtain the voltage coverage range of the first servo error signals in the signal set according to the voltage values ​​of the first servo error signals in the same signal set, and then determine the voltage threshold of the signal set according to the voltage span of the voltage coverage range. For example, when the voltage values ​​of multiple first servo error signals in the signal set are relatively evenly distributed, the median of the voltage coverage range can be determined as the voltage threshold of the signal set. For another example, the distribution density of the voltage values ​​of multiple first servo error signals in the signal set can be analyzed, and then the distribution density can be determined as the weight of the corresponding first servo error signal, and the weighted value of the voltage values ​​of multiple first servo error signals in the signal set can be determined as the voltage threshold of the signal set. Among them, the third signal processing unit can also obtain the total number of signal sets provided to it by the second signal processing unit, and obtain the same number of voltage thresholds according to the total number. In one implementation, after the second signal processing unit obtains multiple signal sets, it can count the total number of the multiple signal sets and provide the total number to the third signal processing unit. In some scenarios, the total number of signal sets corresponds to the capacity of the fluorescent optical disk, so the total number is also called the order. Alternatively, after receiving multiple signal sets provided by the second signal processing unit, the third signal processing unit can obtain the total number of the multiple signal sets by statistical means.

[0081] Optionally, step 704 can be implemented by a U-net neural network. U-net neural networks are a type of convolutional neural networks (CNN). In one implementation, multiple signal sets can be input into the U-net neural network so that the U-net neural network performs feature analysis on the voltage value of the first servo error signal in each signal set, and determines the voltage threshold of the signal set based on the analysis result. The U-net neural network can be obtained by pre-training using a training set. The result of the pre-training can indicate the voltage thresholds of multiple training signal sets. When executing step 704, the voltage thresholds of multiple signal sets can be determined based on the multiple training signal sets. For example, when executing step 704, the voltage thresholds of multiple training signal sets obtained by pre-training can be fine-tuned based on the analysis result of the voltage value of the first servo error signal in each signal set, and the voltage threshold of the corresponding signal set is determined based on the fine-tuned voltage threshold, thereby obtaining the voltage thresholds of multiple signal sets.

[0082] Step 705: The first signal processing unit obtains a second servo error signal based on the adjusted multiple signal sets, and provides the second servo error signal to the servo control unit, where the second servo error signal is used to indicate how the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc changes over time.

[0083] In one implementation, after receiving the adjusted multiple signal sets, the first signal processing unit can obtain the timing of the multiple first servo error signals, and then predict the change trend of the voltage value between the generation moments of the two first servo error signals adjacent to each other based on the voltage values ​​of any two first servo error signals adjacent to each other in timing, and then obtain the second servo error signal based on the change trend and the multiple first servo error signals. For example, the first signal processing unit first sorts all the first servo error signals in the multiple signal sets in the order of timing according to the timing relationship indicated by the generation moments of the first servo error signals in the adjusted multiple signal sets, and then predicts the change trend of the voltage value between the generation moments of the two first servo error signals with time according to the voltage values ​​of any two adjacent first servo error signals in the sorting queue, and fills the voltage waveform indicating the change trend between the waveforms of the two first servo error signals, and so on, the second servo error signal can be obtained by performing the prediction process based on each two adjacent first servo error signals in the sorting queue. Among them, the second servo error signal is used to indicate the situation in which the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc changes with time. It can be seen that the second servo error signal is actually a continuous signal that changes with time. Then, the step 705 is essentially to obtain the second servo error signal presented as a continuous signal based on multiple first servo error signals presented as discrete signals.

[0084] In one implementation, step 705 can be implemented by a long short-term memory (LSTM) neural network. For the structure of the LSTM neural network, please refer to Fig.12 , where X(t-1), X(t) and X(t+1) are the inputs of the LSTM neural network at t-1, t and t+1, i.e., the adjusted multiple signal sets received at t-1, t and t+1, respectively. h(t-1), h(t) and h(t+1) are the outputs of the hidden layer of the LSTM neural network at t-1, t and t+1, i.e., the second servo error signals obtained at t-1, t and t+1, respectively. Please continue to refer to Fig.12, the function of the LSTM neural network is mainly realized by three gates, namely the forget gate, the input layer gate and the output layer gate. The forget gate is used to decide which information to discard from the cell state. The threshold δ1 is used to control the amount of data passing through the forget gate. The value range of δ1 is [0, 1]. δ1 = 0 means "complete retention" and δ1 = 1 means "complete discard". The input layer gate is used to decide which new information needs to be stored in the cell state. Its function is mainly realized by the input threshold layer (δ2) and the tanh1 layer. The input threshold layer (δ2) is used to decide which values ​​to update. The tanh1 layer is used to create a new candidate vector and add it to the cell state. The output layer gate is used to decide the output. Its function is realized by the output threshold layer (δ3) and the tanh2 layer. The output threshold layer (δ3) determines which parts of the cell state need to be output. The tanh2 layer is used to process the cell state and output a value in the range of [-1, 1]. The output of the output layer gate is the product of the output of the output threshold layer (δ3) and the output of the tanh2 layer. Optionally, the values ​​of δ1, δ2 and δ3 can be set according to actual needs.

[0085] By using the LSTM neural network based on the adjusted signal set, a second servo error signal presented as a continuous signal is obtained. The advantages of the LSTM neural network in identifying and predicting continuous signals, as well as the characteristics of long and short-term memory functions, can be used to train and learn possible error signal data sets. By continuously measuring the first servo error signals corresponding to different target positions, deep learning technology is used to identify and predict discrete signals in the time domain. Therefore, discrete signals can be converted into continuous signals, and a high-precision second servo error signal that meets the servo control requirements can be obtained.

[0086] Step 706: The servo control unit obtains an adjusted servo control signal based on the second servo error signal.

[0087] After the servo control unit receives the second servo error signal provided by the first signal processing unit, it can obtain an adjusted servo control signal based on the second servo error signal combined with the current position of the objective lens, so that the servo control unit can control the objective lens according to the adjusted servo control signal in the next adjustment process, so that the objective lens focuses the servo light on the servo surface of the fluorescent optical disc.

[0088] Optionally, before obtaining the servo control signal based on the second servo error signal, the servo control unit may first adaptively adjust the second servo error signal to reduce the error of the second servo error signal, thereby ensuring the accuracy of the adjusted servo control signal obtained based on the second servo error signal and focusing the servo light more accurately on the servo surface of the fluorescent optical disc. In one implementation, the servo control unit may include a lead-lag controller, and the servo control unit may use the lead-lag controller to adaptively adjust the second servo error signal. For example, Fig.13 Schematic diagram of a lead-lag controller provided in an embodiment of the present application. Fig.13 As shown, the input of the lead-lag controller is the second servo error signal, and the output is the adjusted second servo error signal. The transfer function G(s) of the lead-lag controller satisfies the following formula:

[0089]

[0090] Optionally, Fig.14 is a schematic diagram of the structure of another lead-lag controller provided in an embodiment of the present application. Fig.14 As shown, the lead-lag controller includes a repetitive control link and a lead-lag control link. Fig.13 The lead-lag controller shown in the figure adds a repetitive control link. The repetitive control link can first perform multiple rounds of automatic adjustment on the second servo error signal, and then provide the adjusted second servo error signal to the lead-lag control link to further improve the accuracy of the adjusted second servo error signal. Fig.14 The lead-lag controller transfer function G(s) shown satisfies the following equation:

[0091]

[0092] Among them, Cr(s) is the transfer function of the repetitive control link, which satisfies:

[0093] Furthermore, the servo control unit may also include a proportional (P), integral (I), and differential (D) controller (PID controller). The input of the PID controller is the second servo error signal, and the output is the second servo error signal adjusted by the PID controller. Furthermore, when the servo control unit also includes a PID controller, the second servo error signal may be adjusted using the PID controller first, and then the second servo error signal may be adjusted using the lead-lag controller. In one implementation, the PID controller may be a fuzzy adaptive PID controller. Since the fuzzy adaptive PID controller can adjust the PID parameters in real time, the second servo error signal may be adjusted more accurately. Fig.15It is a structural diagram of a fuzzy adaptive PID controller provided in an embodiment of the present application.

[0094] As can be seen from the above, in the servo control method of the fluorescent optical disc provided in the embodiment of the present application, the servo control unit can control the optical processing unit based on the initial servo control signal, and focus the servo light on the servo surface of the fluorescent optical disc through the optical processing unit. Then, the optical receiver can receive the servo feedback light of the fluorescent optical disc to the servo light, and obtain multiple first servo error signals based on the servo feedback light, and provide multiple first servo error signals to the first signal processing unit. Then, the first signal processing unit obtains the second servo error signal based on the multiple first servo error signals. Since the first servo error signal is used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc. The first servo error signal is expressed as a discrete signal. The second servo error signal is used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc changes over time. The second servo error signal is expressed as a continuous signal. Through the processing of the first servo error signal by the first signal processing unit, the first servo error signal is converted into a second servo error signal presented as a continuous signal. After the first signal processing unit provides the second servo error signal to the servo control unit, the servo control unit can obtain an adjusted servo control signal based on the second servo error signal presented as a continuous signal.

[0095] In this way, during the servo control process, taking into account that the servo feedback light fed back by the fluorescent optical disc presents a discrete characteristic, the servo feedback light presenting a discrete characteristic can be converted into a second servo error signal presenting a continuous signal through the processing of the optical receiver and the first signal processing unit. There is no need to use a continuous signal as the signal fed back by the servo light for servo control, which effectively improves the accuracy of servo control based on the servo feedback light fed back by the fluorescent optical disc, and helps to improve the reading and writing characteristics of the fluorescent optical disc.

[0096] When a neural network is used to implement the first signal processing unit, the second signal processing unit and / or the third signal processing unit, the advantages of the neural network can be utilized to improve the signal processing speed when processing the signal, and to improve the speed of reading and writing data from the fluorescent optical disc, so that the method can also be applied to the reading scene of high-speed optical discs or high-density fluorescent storage systems. Similarly, those skilled in the art can also apply the method to the processing and classification of high-speed discrete signals based on the idea of ​​the servo control method provided in the embodiment of the present application, for example, in the encoding of the information spot position and its signal amplitude change, or in the determination of the threshold voltage when counting high-frequency pulses.

[0097] Moreover, when the neural network used to implement the first signal processing unit, the second signal processing unit and / or the third signal processing unit is a pre-trained neural network, a large amount of data training can be used to improve the accuracy of classification judgment, and the neural network can be used continuously after the data set training is established without adjusting the parameters, thereby improving the convenience of implementing the servo control method.

[0098] It should be noted that the sequence of steps of the servo control method for a fluorescent optical disc provided in the embodiment of the present application can be adjusted appropriately, and the steps can be increased or decreased accordingly according to the situation. Any technician familiar with the technical field can easily think of a change within the technical scope disclosed in the present application, and the change should be included in the protection scope of the present application, so it will not be repeated.

[0099] The above describes the servo control method of the fluorescent optical disc in the embodiment of the present application. Corresponding to the above method, the embodiment of the present application also provides a servo control device. The structural schematic diagram of the servo control device is shown in FIG. Figure 4 and Figure 5 It should be understood that the servo control device may include more additional units than the structure shown or omit some of the units shown therein, and the present application embodiment does not limit this. Figure 4 As shown, the servo control device includes: a servo control unit, an optical processing unit, a light receiver and a first signal processing unit.

[0100] The servo control unit is used to control the optical processing unit based on the servo control signal, so that the servo light is focused on the servo surface of the fluorescent optical disk via the optical processing unit.

[0101] The optical receiver is used to receive servo feedback light of the fluorescent optical disc to the servo light, obtain multiple first servo error signals based on the servo feedback light, and provide multiple first servo error signals to the first signal processing unit. The first servo error signals are used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc.

[0102] The first signal processing unit is used to obtain a second servo error signal based on multiple first servo error signals, and provide the second servo error signal to the servo control unit. The second servo error signal is used to indicate how the distance between the spot position of the servo light on the fluorescent optical disc and the target point position of the fluorescent optical disc changes over time.

[0103] The servo control unit is further configured to obtain an adjusted servo control signal based on the second servo error signal.

[0104] Optionally, the first signal processing unit is specifically used to: obtain the timing of multiple first servo error signals; predict the changing trend of the voltage value between the generation moments of any two first servo error signals adjacent in timing based on the voltage values ​​of any two first servo error signals adjacent in timing; and obtain the second servo error signal based on the changing trend and multiple first servo error signals.

[0105] Optionally, the device further comprises: a second signal processing unit. The second signal processing unit is configured to: receive a plurality of first servo error signals provided by the optical receiver; divide the plurality of first servo error signals into a plurality of signal sets; and provide the plurality of signal sets to the first signal processing unit.

[0106] Optionally, the second signal processing unit is specifically configured to: divide the plurality of first servo error signals into a plurality of signal sets based on distribution of voltage values ​​of the plurality of first servo error signals.

[0107] Optionally, the device further includes: a third signal processing unit. The third signal processing unit is used to: receive multiple signal sets provided by the second signal processing unit; obtain a voltage threshold of any signal set based on the voltage value of the first servo error signal in any signal set; adjust the voltage of the first servo error signal in any signal set based on the voltage threshold of any signal set to obtain multiple adjusted signal sets; and provide the multiple adjusted signal sets to the first signal processing unit.

[0108] Optionally, the third signal processing unit is specifically used to: obtain a voltage coverage range of the first servo error signal in any signal set based on the voltage value of the first servo error signal in any signal set; and determine a voltage threshold of any signal set based on the voltage coverage range of any signal set.

[0109] Optionally, the voltage of the adjusted first servo error signal is equal to a voltage threshold of a signal set to which the first servo error signal belongs.

[0110] Optionally, the light receiving unit is a photomultiplier tube.

[0111] Based on the above various implementations, further combinations can be made to provide more implementations.

[0112] As can be seen from the above, in the servo control device of the fluorescent optical disc provided in the embodiment of the present application, the servo control unit can control the optical processing unit based on the initial servo control signal, and focus the servo light on the servo surface of the fluorescent optical disc through the optical processing unit. Then, the optical receiver can receive the servo feedback light of the fluorescent optical disc to the servo light, and obtain multiple first servo error signals based on the servo feedback light, and provide multiple first servo error signals to the first signal processing unit. Then, the first signal processing unit obtains the second servo error signal based on the multiple first servo error signals. Since the first servo error signal is used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc. The first servo error signal is expressed as a discrete signal. The second servo error signal is used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc changes over time. The second servo error signal is expressed as a continuous signal. Through the processing of the first servo error signal by the first signal processing unit, the first servo error signal is converted into a second servo error signal presented as a continuous signal. After the first signal processing unit provides the second servo error signal to the servo control unit, the servo control unit can obtain an adjusted servo control signal based on the second servo error signal presented as a continuous signal.

[0113] In this way, during the servo control process, taking into account that the servo feedback light fed back by the fluorescent optical disc presents a discrete characteristic, the servo feedback light presenting a discrete characteristic can be converted into a second servo error signal presenting a continuous signal through the processing of the optical receiver and the first signal processing unit. There is no need to use a continuous signal as the signal fed back by the servo light for servo control, which effectively improves the accuracy of servo control based on the servo feedback light fed back by the fluorescent optical disc, and helps to improve the reading and writing characteristics of the fluorescent optical disc.

[0114] When a neural network is used to implement the first signal processing unit, the second signal processing unit and / or the third signal processing unit, the advantages of the neural network can be utilized to improve the signal processing speed when processing the signal, and to improve the speed of reading and writing data from the fluorescent optical disc, so that the device can also be applied to the reading scene of high-speed optical discs or high-density fluorescent storage systems. Similarly, those skilled in the art can also apply the device to the processing and classification of high-speed discrete signals based on the concept of the servo control device provided in the embodiment of the present application, for example, in the encoding of the information spot position and its signal amplitude change, or in the determination of the threshold voltage when counting high-frequency pulses.

[0115] Moreover, when the neural network used to implement the first signal processing unit, the second signal processing unit and / or the third signal processing unit is a pre-trained neural network, a large amount of data training can be used to improve the accuracy of classification judgment, and the neural network can be used continuously after the data set training is established without adjusting the parameters, thereby improving the convenience of implementation of the servo control device.

[0116] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of each unit described above can refer to the corresponding content in the aforementioned method embodiment, and will not be repeated here.

[0117] The embodiment of the present application provides a data reading and writing device. The data reading and writing device performs some or all functions of the servo control device provided by the present application. For example, the data reading and writing device controls each unit in the servo control device of the fluorescent optical disc to execute the corresponding method in the servo control method of the fluorescent optical disc. Fig.16 Schematic diagram of the structure of a data reading and writing device provided in an embodiment of the present application. Fig.16 As shown, the data reading and writing device 1600 includes a processor 1601, a memory 1602, a communication interface 1603 and a bus 1604. The processor 1601, the memory 1602 and the communication interface 1603 are connected to each other through the bus 1604.

[0118] Processor 1601 may include a general processor and / or a dedicated hardware chip. A general processor may include: a central processing unit (CPU), a microprocessor or a graphics processing unit (GPU). The CPU is, for example, a single-core processor (single-CPU) or a multi-core processor (multi-CPU). A dedicated hardware chip is a hardware module for high-performance processing. A dedicated hardware chip includes at least one of a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or a network processor (NP). Processor 1601 may also be an integrated circuit chip having signal processing capabilities. In the implementation process, part or all of the functions of the servo control method for the fluorescent optical disc of the present application may be completed by the hardware integrated logic circuit in the processor 1601 or instructions in the form of software.

[0119] The memory 1602 is used to store computer programs, which include an operating system 1602a and executable code (i.e., program instructions) 1602b. The memory 1602 is, for example, a read-only memory or other types of static storage devices that can store static information and instructions, or a random access memory or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory, a read-only optical disc or other optical disc storage, an optical disc storage (including a compressed optical disc, a laser disc, an optical disc, a digital versatile disc, a blue-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired executable code in the form of an instruction or data structure and can be accessed by a computer, but is not limited thereto. For example, the memory 1602 is used to store an outbound port queue, etc. The memory 1602 is, for example, independent and connected to the processor 1601 via a bus 1604. Or the memory 1602 and the processor 1601 are integrated together. The memory 1602 can store executable codes. When the executable codes stored in the memory 1602 are executed by the processor 1601, the processor 1601 is used to execute part or all of the functions of the servo control method for the fluorescent optical disk provided in the embodiment of the present application. For the implementation of the process executed by the processor 1601, please refer to the relevant description in the above embodiment. The memory 1602 may also include software modules and data required for other running processes such as the operating system.

[0120] The communication interface 1603 uses a transceiver module such as, but not limited to, a transceiver to achieve communication with other devices or communication networks. For example, the communication interface 1603 can be any one or any combination of the following devices: a network interface (such as an Ethernet interface), a wireless network card, and other devices with network access functions.

[0121] The bus 1604 is any type of communication bus for interconnecting the internal devices (e.g., the memory 1602, the processor 1601, and the communication interface 1603) of the data reading and writing device. For example, a system bus. The embodiment of the present application takes the interconnection of the above-mentioned devices inside the data reading and writing device through the bus 1604 as an example. Optionally, the above-mentioned devices inside the data reading and writing device 1600 can also be connected to each other in communication with each other using other connection methods other than the bus 1604. For example, the above-mentioned devices inside the data reading and writing device 1600 are interconnected through an internal logical interface.

[0122] It should be noted that the above-mentioned multiple devices can be respectively arranged on independent chips, or at least partially or completely arranged on the same chip. Whether to independently arrange each device on different chips or to integrate and arrange it on one or more chips often depends on the needs of product design. The embodiments of the present application do not limit the specific implementation form of the above-mentioned devices. The descriptions of the processes corresponding to the above-mentioned figures have different focuses. For the parts not described in detail in a certain process, please refer to the relevant descriptions of other processes.

[0123] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product providing a program development platform includes one or more computer instructions. When these computer program instructions are loaded and executed on a data reading and writing device, all or part of the functions of the servo control method for a fluorescent optical disk provided in the embodiments of the present application are implemented in whole or in part.

[0124] Furthermore, computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, computer instructions may be transmitted from one website, computer, server or data center to another website, computer, server or data center via wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium stores computer program instructions that provide a program development platform.

[0125] An embodiment of the present application also provides a computer-readable storage medium, which is a non-volatile computer-readable storage medium. The computer-readable storage medium includes program instructions. When the program instructions are executed on a data reading and writing device, the data reading and writing device implements the servo control method of the fluorescent optical disk provided in the embodiment of the present application.

[0126] The embodiment of the present application further provides a computer program product including instructions. When the computer program product is executed on a computer, the computer implements the servo control method for the fluorescent optical disk provided in the embodiment of the present application.

[0127] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware, or by a program to instruct the relevant hardware, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0128] It should be noted that the information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data used for analysis, stored data, displayed data, etc.) and signals involved in this application are all authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with the relevant laws, regulations and standards of relevant countries and regions. For example, the information and executable code involved in this application are all obtained with full authorization.

[0129] In the embodiments of the present application, the terms "first", "second" and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "at least one" means one or more, and the term "plurality" means a plurality, unless otherwise expressly defined.

[0130] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0131] It should be understood that the terms used in the description of various examples herein are only for describing specific examples and are not intended to be limiting. As used in the description of various examples and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0132] It should also be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0133] The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the concepts and principles of the present application should be included in the protection scope of the present application.

Claims

1. A servo control method for a fluorescent optical disc, characterized in that: The method is applied to a servo control device of a fluorescent optical disc, the servo control device of the fluorescent optical disc comprises: a servo control unit, an optical processing unit, a light receiver and a first signal processing unit, and the method comprises: The servo control unit controls the optical processing unit based on the servo control signal so that the servo light is focused on the servo surface of the fluorescent optical disk via the optical processing unit; The optical receiver receives servo feedback light of the fluorescent optical disc to the servo light, obtains a plurality of first servo error signals based on the servo feedback light, and provides the plurality of first servo error signals to the first signal processing unit, wherein the first servo error signals are used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target point position of the fluorescent optical disc; The first signal processing unit obtains a second servo error signal based on the multiple first servo error signals, and provides the second servo error signal to the servo control unit, wherein the second servo error signal is used to indicate how the distance between the spot position of the servo light on the fluorescent optical disk and the target point position of the fluorescent optical disk changes over time; The servo control unit obtains an adjusted servo control signal based on the second servo error signal.

2. The method according to claim 1, characterized in that The first signal processing unit obtains a second servo error signal based on the plurality of first servo error signals, comprising: The first signal processing unit acquires a timing of the plurality of first servo error signals; The first signal processing unit predicts a change trend of the voltage value between the generation moments of any two first servo error signals adjacent in time sequence based on the voltage values ​​of the first servo error signals adjacent in time sequence; The first signal processing unit obtains the second servo error signal based on the change trend and the plurality of first servo error signals.

3. The method according to claim 1 or 2, characterized in that The servo control device for the fluorescent optical disc further includes: a second signal processing unit, and the method further includes: The second signal processing unit receives the plurality of first servo error signals provided by the optical receiver; The second signal processing unit divides the plurality of first servo error signals into a plurality of signal sets; The second signal processing unit provides the plurality of signal sets to the first signal processing unit.

4. The method according to claim 3, characterized in that The second signal processing unit divides the plurality of first servo error signals into a plurality of signal sets, including: The second signal processing unit divides the plurality of first servo error signals into the plurality of signal sets based on distribution of voltage values ​​of the plurality of first servo error signals.

5. The method according to claim 3, characterized in that The servo control device for the fluorescent optical disc further includes: a third signal processing unit, and the method further includes: The third signal processing unit receives the plurality of signal sets provided by the second signal processing unit; The third signal processing unit acquires a voltage threshold of any signal set based on a voltage value of the first servo error signal in any signal set; The third signal processing unit adjusts the voltage of the first servo error signal in any signal set based on the voltage threshold of any signal set to obtain a plurality of adjusted signal sets; The third signal processing unit provides the adjusted plurality of signal sets to the first signal processing unit.

6. The method according to claim 5, characterized in that The third signal processing unit acquires a voltage threshold of any signal set based on a voltage value of the first servo error signal in any signal set, including: The third signal processing unit obtains a voltage coverage range of the first servo error signal in any signal set based on the voltage value of the first servo error signal in any signal set; The third signal processing unit determines a voltage threshold of any signal set based on a voltage coverage range of any signal set.

7. The method according to claim 5, characterized in that The voltage of the adjusted first servo error signal is equal to a voltage threshold of the signal set to which the first servo error signal belongs.

8. A servo control device for a fluorescent optical disc, characterized in that: The device comprises: a servo control unit, an optical processing unit, an optical receiver and a first signal processing unit; The servo control unit is used to control the optical processing unit based on the servo control signal, so that the servo light is focused on the servo surface of the fluorescent optical disk through the optical processing unit; The optical receiver is used to receive servo feedback light of the fluorescent optical disc to the servo light, obtain a plurality of first servo error signals based on the servo feedback light, and provide the plurality of first servo error signals to the first signal processing unit, wherein the first servo error signals are used to indicate the distance between the spot position of the servo light on the fluorescent optical disc and the target position of the fluorescent optical disc; The first signal processing unit is used to obtain a second servo error signal based on the multiple first servo error signals, and provide the second servo error signal to the servo control unit, wherein the second servo error signal is used to indicate how the distance between the spot position of the servo light on the fluorescent optical disk and the target point position of the fluorescent optical disk changes over time; The servo control unit is further configured to obtain an adjusted servo control signal based on the second servo error signal.

9. The device according to claim 8, characterized in that The first signal processing unit is specifically used for: Acquiring a timing sequence of the plurality of first servo error signals; Based on the voltage values ​​of any two first servo error signals that are adjacent in time sequence, predicting the change trend of the voltage value between the generation moments of the any two first servo error signals that are adjacent in time sequence; Based on the variation trend and the plurality of first servo error signals, the second servo error signal is obtained.

10. The device according to claim 8 or 9, characterized in that The device further includes: a second signal processing unit, wherein the second signal processing unit is configured to: receiving the plurality of first servo error signals provided by the optical receiver; dividing the plurality of first servo error signals into a plurality of signal sets; The plurality of signal sets are provided to the first signal processing unit.

11. The device according to claim 10, characterized in that The second signal processing unit is specifically used for: The plurality of first servo error signals are divided into the plurality of signal sets based on distribution of voltage values ​​of the plurality of first servo error signals.

12. The device according to claim 10, characterized in that The device further includes: a third signal processing unit, wherein the third signal processing unit is configured to: receiving the plurality of signal sets provided by the second signal processing unit; Based on the voltage value of the first servo error signal in any signal set, obtaining a voltage threshold of any signal set; Based on the voltage threshold of any one of the signal sets, adjusting the voltage of the first servo error signal in any one of the signal sets to obtain a plurality of adjusted signal sets; The adjusted plurality of signal sets are provided to the first signal processing unit.

13. The device according to claim 12, characterized in that The third signal processing unit is specifically used for: Based on the voltage value of the first servo error signal in any one of the signal sets, obtaining a voltage coverage range of the first servo error signal in any one of the signal sets; Based on the voltage coverage of any one of the signal sets, a voltage threshold of any one of the signal sets is determined.

14. The device according to claim 12, characterized in that The voltage of the adjusted first servo error signal is equal to a voltage threshold of the signal set to which the first servo error signal belongs.

15. The device according to claim 8, characterized in that The light receiving unit is a photomultiplier tube PMT.

16. A data reading and writing device for a fluorescent optical disc, characterized in that: The data reading and writing device comprises the servo control device for the fluorescent optical disk as claimed in any one of claims 8 to 15.

17. A computer program product comprising instructions, characterized in that When the instruction is executed by the data reading and writing device, the data reading and writing device executes the method according to any one of claims 1 to 7.

18. A computer-readable storage medium, characterized in that: The method comprises computer program instructions. When the computer program instructions are executed by a data reading and writing device, the data reading and writing device executes the method according to any one of claims 1 to 7.

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