A control method

Abstract

A control method, device and system, the method can be applied to the optical drive, the method comprises: the optical drive projects first laser beam to the tilt detection layer of the optical disc through the laser head, and detects the first reflected light signal; wherein, the first reflected light signal is the light signal of the first laser beam reflected by the tilt detection layer; the optical drive generates the first tracking error TE signal based on the first reflected light signal; the optical drive adjusts the tilt angle between the laser head and the optical disc to the first angle according to the first TE signal, so that the peak to peak value MMP of the first TE signal remains at the first set value.

Description

Technical Field

[0001] This application relates to the field of optical storage, and more particularly to a control method. Background Technology

[0002] In the field of optical storage, optical discs are mainly used to store data. In terms of optical disc capacity, the common CD capacity is about 700MB, DVD can reach 4.7GB, and Blu-ray discs can reach 25GB or even higher. Magnetic material storage devices, such as hard drives, have capacities ranging from hundreds of GB to several TB or even higher. Overall, magnetic materials have more advantages in large-capacity storage. However, due to the higher stability, longer lifespan, and lower cost of optical discs, if the capacity of optical discs can be increased, it is expected to reshape the storage industry landscape.

[0003] Current optical discs are typically multi-layered, with the capacity of a single disc equal to the number of layers multiplied by the capacity of each layer. In the current optical storage market, the mainstream method for increasing capacity is to increase the storage density of each layer. However, this approach has now nearly reached the limits of material performance and servo control technology. Therefore, the industry has turned its attention to the innovative research and development direction of increasing the number of optical disc layers to expand capacity. Currently, this technology is still in the laboratory exploration stage. Future optical drives are expected to achieve ultra-high capacity storage targets of 500GB to 2TB per disc by leveraging this strategy of increasing the number of layers. However, this cutting-edge technology still faces many thorny challenges on its path to practical application. The most prominent is the tilt control problem between the optical disc and the objective lens. The thicker the disc, the higher the precision required for tilt control. Once tilting occurs between the disc and the objective lens, it will cause the track to be squeezed and deformed, seriously affecting the accuracy and stability of data reading and writing. Current tilt control precision for multi-layered discs cannot meet commercial requirements, becoming a key bottleneck restricting the technology's implementation. Summary of the Invention

[0004] This application provides a control method for improving the tilt control accuracy of multi-layer optical discs.

[0005] In a first aspect, this application provides a control method applicable to an optical drive. The optical drive includes a laser head, a photoelectric detection component, and a control device (such as a main control chip). The method can be executed by the optical drive or by a component of the optical drive (such as the control device). Taking the control device as an example, the method includes: the control device projects a first laser beam (such as blue light) onto the tilt detection layer of the optical disc through the laser head, and receives the light signal reflected back from the optical disc by the first laser beam through the photoelectric detection component (denoted as the first reflected light signal); then, the optical drive generates a Track Error (TE) signal based on the first reflected light signal through the photoelectric detection component (the TE signal generated based on the first reflected light signal is denoted as the first TE signal); the control device adjusts the tilt angle between the laser head and the optical disc to a first angle according to the first TE signal, so that the maximum peak-to-peak (MPP) of the first TE signal is kept at a first set value.

[0006] Using the above method, the optical drive adjusts the tilt angle between the laser head and the optical disc (referred to as the optical disc tilt angle) according to the first TE signal. Based on the experimental data, the MPP of the first TE signal and the tilt angle of the optical disc are adjusted so that the MPP of the first TE signal is kept at the first set value. At this time, the tilt angle of the optical disc is less than the tilt angle required for traditional multi-layer optical discs, which can meet the higher tilt accuracy requirements, thereby supporting the setting of more recording layers on the optical disc to increase the storage capacity of the optical disc.

[0007] In one possible design of the first aspect, the control device adjusts the tilt angle between the laser head and the optical disc to a first angle based on the first TE, comprising: the control device gradually adjusting the tilt angle between the laser head and the optical disc via a tilt servo; the control device monitoring the MPP of the first TE signal detected by the PDIC during the adjustment process, the MPP of the first TE signal being determined based on the first reflected light signal of the first laser beam in the focused state of the tilt detection layer; when the MPP of the first TE signal is at a first set value, the adjustment of the tilt angle of the laser head is stopped; when the adjustment of the tilt angle of the laser head is stopped, the tilt angle between the laser head and the optical disc is the first angle.

[0008] Using the above method, the control device gradually adjusts the tilt angle to achieve fine-tuning of the tilt angle and realize higher adjustment accuracy.

[0009] In one possible design of the first aspect, the optical drive further includes a servo system, and the method further includes: a control device controlling the servo system to move the laser head laterally, thereby causing the first laser beam to track on the target track of the tilt detection layer; the control device detecting the width of the target track track tracked by the first laser beam, and adjusting the tilt angle between the laser head and the optical disc from a first angle to a second angle based on the detected target track width, so that the width of the detected target track remains at a second set value. The second angle is smaller than the first angle.

[0010] By using the above method, the tilt angle of the optical disc can be adjusted based on the width of the target track, thereby reducing the tilt angle to a smaller angle and meeting higher precision control requirements.

[0011] In one possible design of the first aspect, the optical drive also includes a tilt servo; the width of the target track detected by the control device is correlated with the servo loop gain of the servo system; for example, the width of the target track detected by the control device is proportional to the servo loop gain, and the larger the servo loop gain, the larger the width of the detected target track.

[0012] The control device adjusts the tilt angle between the laser head and the optical disc from a first angle to a second angle based on the width of the target track. This includes: the control device gradually adjusting the horizontal angle of the laser head via a tilt servo; for example, controlling the laser head to rotate by a set angle each time, thereby gradually reducing the tilt angle. The control device monitors the servo loop gain of the servo system during the tilt angle adjustment process; when the servo loop gain reaches a third set value, the control device stops adjusting the tilt angle of the laser head. At this point, the tilt angle between the laser head and the optical disc is the second angle.

[0013] Through the above design, the width of the target track can be accurately measured based on the servo loop gain, thereby improving the accuracy of adjusting the tilt angle based on the correlation between the width of the target track and the tilt angle of the optical disc.

[0014] In one possible design of the first aspect, the control device monitors the servo loop gain of the cyclic servo during the adjustment process, including: during the adjustment of the tilt angle of the laser head, the control device acquires the control information of the servo adjustment system and the position information of the laser head; then, the control device calculates the servo loop gain based on the acquired control information and position information.

[0015] In one possible design of the first aspect, the method further includes: a control device projecting a second laser beam onto the target recording layer of the optical disc via a laser head, detecting the light signal reflected from the optical disc by the second laser beam (denoted as the second reflected light signal), and generating a tracking error signal (denoted as the second TE signal) based on the second reflected light signal; the control device projecting a third laser beam onto the tilt detection layer of the optical disc via a laser head, detecting the light signal reflected from the optical disc by the third laser beam (denoted as the third reflected light signal), and generating a tracking error signal (denoted as the third TE signal) based on the third reflected light signal; then, the control device adjusting the position of the objective lens according to the second TE signal and the third TE signal, stopping the adjustment of the objective lens position when the time-domain waveforms of the second TE signal and the third TE signal are synchronized, at which point the tilt angle of the optical disc is the third angle; the third angle is less than the second angle.

[0016] Through the above design, the optical drive can synchronize the time-domain waveforms of the second TE signal and the third TE signal by adjusting the position of the objective lens, thereby making the red light and blue light coaxial. This solves the overwriting problem caused by the non-coaxial nature of the existing red and blue light, and enables multi-layer optical discs with larger capacity to meet the precision control requirements of commercial applications.

[0017] In one possible design of the first aspect, the control device adjusts the tilt angle between the laser head and the optical disc from a second angle to a third angle based on the second TE signal and the third TE signal, including: the optical drive gradually adjusts the tilt angle of the laser head through a tilt servo, and controls the laser head through the servo system to make the third laser head track in the tilt detection layer; the control device monitors the time-domain waveforms of the second TE signal and the third TE signal collected during the adjustment of the tilt angle of the laser head; when the time-domain waveforms of the second TE signal and the third TE signal are synchronized, the adjustment of the tilt angle of the laser head is stopped; when the adjustment of the tilt angle between the laser head and the optical disc is stopped, the tilt angle between the laser head and the optical disc is the third angle.

[0018] In one possible design of the first aspect, the first angle is no greater than 0.45 degrees, the second angle is no greater than 0.05 degrees, and the third angle is no greater than 0.02 degrees.

[0019] Through the above design, the optical drive can gradually adjust the tilt angle of the optical disc to different values ​​to meet different precision control requirements.

[0020] In one possible design of the first aspect, the optical disc includes an independent boot layer and multiple recording layers, each recording layer for storing data, an independent boot layer for storing servo information, the independent boot layer being located below the multiple recording layers, and a tilt detection layer being an independent boot layer.

[0021] By reusing the independent boot layer as the tilt detection layer through the above design, the cost of optical discs can be saved.

[0022] Secondly, this application also provides a control device that has the function of implementing the control device behavior in the method described in the first aspect and any possible design of the first aspect. The beneficial effects can be found in the description of the first aspect, and will not be repeated here. The function can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-described functions. In one possible design, the device structure includes a control module, an acquisition module, and an adjustment module; these modules can implement the function of controlling the device behavior in the method described in the first aspect and any possible design of the first aspect, as detailed in the method examples, and will not be repeated here.

[0023] Thirdly, this application also provides a control device. The control device includes a control circuit and a power supply system, the power supply system being used to supply power to components (such as the control circuit) in the control device. The control circuit is used to perform the functions of the control device in the first aspect and any possible design of the first aspect.

[0024] Fourthly, this application also provides a control system, such as an optical drive, which includes the control device described in the second or third aspect, a laser, and other components. Optionally, the control system further includes a servo system. The control device is used to execute the methods described in the first aspect and various possible designs of the first aspect, and the laser and servo system are the controlled objects in which the control device executes the methods.

[0025] Fifthly, this application also provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the methods described in the first aspect and various possible designs of the first aspect.

[0026] In a sixth aspect, this application also provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the methods described in the first aspect and various possible designs of the first aspect.

[0027] In a seventh aspect, this application also provides a computing chip connected to a memory, which is used to read and execute a software program stored in the memory to perform the methods described in the first aspect and various possible implementations of the first aspect.

[0028] For the description of the beneficial effects of any of the second to seventh aspects above, please refer to the description of the technical effects in any possible implementation of the first aspect above, and this application will not repeat it here. Attached Figure Description

[0029] Figure 1This is a schematic diagram of a system architecture provided in an embodiment of this application;

[0030] Figure 2 This is a schematic diagram of the structure of an optical drive provided in an embodiment of this application;

[0031] Figure 3 This is a schematic diagram of a multi-layer optical disc provided in an embodiment of this application;

[0032] Figure 4 This is a complete flowchart of a control method provided in an embodiment of this application;

[0033] Figure 5 This is a flowchart illustrating the first control method provided in the embodiments of this application;

[0034] Figure 6 This is a schematic diagram of the optical path of a first laser beam provided in an embodiment of this application;

[0035] Figure 7 This is a waveform diagram of the first TE signal monitored during the tilt angle adjustment process in the first embodiment of this application;

[0036] Figure 8 This is a schematic diagram illustrating the relationship between the MPP of a first TE signal and the tilt angle of an optical disc, provided in an embodiment of this application.

[0037] Figure 9 This is a schematic diagram of a data write operation at a tilt angle provided in an embodiment of this application;

[0038] Figure 10 This is a schematic diagram of another tilt angle data write operation provided in an embodiment of this application;

[0039] Figure 11 This is a flowchart illustrating the second control method provided in the embodiments of this application;

[0040] Figure 12 This is a schematic diagram of the control flow of a tracking servo according to an embodiment of this application;

[0041] Figure 13 This is a schematic diagram illustrating the relationship between servo loop gain and optical disc tilt angle provided in an embodiment of this application;

[0042] Figure 14 This is a flowchart illustrating the third control method provided in the embodiments of this application;

[0043] Figure 15A This is a schematic diagram of a data writing scenario provided in an embodiment of this application;

[0044] Figure 15BThis is a schematic diagram of another data writing scenario provided in an embodiment of this application;

[0045] Figure 16 This is a schematic diagram of waveform synchronization provided in an embodiment of this application;

[0046] Figure 17 This is a schematic diagram of another waveform synchronization provided in an embodiment of this application;

[0047] Figure 18 This is a schematic diagram of the structure of a control device provided in an embodiment of this application;

[0048] Figure 19 This is a schematic diagram of another control device provided in an embodiment of this application. Detailed Implementation

[0049] To better understand the solutions of the embodiments of this application, some related terms and concepts that may be involved in the embodiments of this application will be introduced below:

[0050] 1. CD

[0051] Optical discs are optical storage media used to store data such as text, sound, graphics, images, and animations. They include compact disc read-only memory (CD-ROM), digital video disc read-only memory (DVD-ROM), compact disk rewritable (CD-RW), and digital versatile disc-random access memory (DVD-RAM).

[0052] CD-ROMs have the longest history of development, originating in 1982 for storing software, music, and data. DVD technology became widespread in 2000, increasing single-disc capacity to 4.7GB. Blu-ray (BD) technology was commercialized in 2006, offering 25GB per disc (single layer), driving the development of high-definition movies and games. Current optical discs have multi-layered structures, such as the Blu-ray dual-layer disc, which includes two recording layers. The recording layer is the part of the disc used for actual data storage, with a single-disc (dual-layer) capacity reaching 50GB. Future optical discs may achieve even more layers.

[0053] 2. Optical drive

[0054] An optical drive is a device for reading and writing data on optical discs. The tracks on an optical disc are arranged in a spiral pattern, and the optical drive reads data by moving radially (similar to the needle of a record player) along the tracks. For example, when writing data to an optical disc, the optical drive can emit a laser and focus it into a laser beam, which is then directed onto the tracks of the disc to melt the recording medium, forming a small pit, thereby changing its optical properties. When the optical drive reads data from the disc, the photoelectric detection circuitry in the optical drive can read the data stored on the disc based on the difference in light reflectivity between the laser-burned and unburned recording media.

[0055] In this application embodiment, "multiple" refers to two or more. Therefore, in this application embodiment, "multiple" can also be understood as "at least two". "At least one" can be understood as one or more, such as one, two, or more. For example, "including at least one" means including one, two, or more, and it does not limit which ones are included. For example, including at least one of A, B, and C, then it could include A, B, C, A and B, A and C, B and C, or A and B and C. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.

[0056] Unless otherwise stated, the ordinal numbers such as "first" and "second" mentioned in the embodiments of this application are used to distinguish multiple objects, and are not used to limit the order, sequence, priority or importance of multiple objects.

[0057] Figure 1 This application provides an embodiment of an optical storage system 10, which includes a control system 20 and an optical disc 30. The control system 20 is a device for reading and writing data on the optical disc, such as an optical drive. For ease of explanation, the following description uses an optical drive as an example of the control system 20; the optical drive in the following text can be replaced by the control system 20. The optical disc 30 is used to store data.

[0058] The optical storage system 10 can be widely used in various scenarios. For example, in data storage scenarios, the optical disc 30 is used to store computer program code and user data of the operating system or software, and the control system 20 is used to read and write the computer program code and data in the optical disc 30; in multimedia entertainment scenarios, the control system 20 is used to play music, movies, games, etc. stored in the optical disc 30; in car navigation systems, the control system 20 is used to read map data stored in the optical disc 30; in the medical field, the optical disc 30 is used to store patient image data; in the aerospace field, the optical disc 30 is used to store flight data recordings and verification information, etc. This application does not limit the applicable scenarios of the optical storage system 10.

[0059] When the optical drive 20 reads or writes data to the optical disc 30, the optical disc 30 needs to be placed in the control system 20. In specific application scenarios, the optical drive 20 can be installed in an electronic device. When the optical disc 30 is inserted into the optical drive 20 of the electronic device, the electronic device can read data from the optical disc 30 or write data to the optical disc 30 through the optical drive 20. The electronic device can be any device with computing capabilities, such as a CD player, DVD player, server, laptop, desktop computer, car media player, etc., without specific limitations.

[0060] Figure 2 This is a schematic diagram of the structure of an optical drive 20 provided in an embodiment of this application. For example... Figure 2 As shown, the optical drive 20 includes: a laser head 21, a servo system 22, and a control device 23.

[0061] 1. Laser head 21.

[0062] Functionally, the laser head 21 is responsible for reading or writing optical disc data using laser technology. In terms of hardware, the laser head 21 includes a laser emitting assembly 210, a grating 211, an objective lens 212, and a photoelectric detection assembly 213.

[0063] A laser emitting component 210 is used to emit a laser beam of a specific wavelength. The laser emitting component 210 mainly consists of laser diodes and can emit lasers of different wavelengths and powers. For example, a laser diode can emit red light with a wavelength of approximately 650 nm and blue light with a wavelength of approximately 405 nm. The laser emitting component 210 may include one or more laser diodes. Typically, a single laser diode can only emit light of one wavelength. Therefore, the laser emitting component 210 in this embodiment includes at least two laser diodes, referred to as a blue diode and a red diode, respectively. The blue diode is used to emit blue light, while the red diode is used to emit red light. It should be noted that the red diode is not limited to emitting red light with a wavelength of 650 nm; for example, the red light emitted by the optical drives of early CD players was approximately 780 nm. The blue diode is not limited to emitting blue light with a wavelength of 405 nm; this application does not limit this. Different wavelengths of light, when focused, form different spot sizes; therefore, wavelength can determine data storage density. For ease of explanation, the default wavelength for red light mentioned below is 650 nm, and the default wavelength for blue light is 405 nm.

[0064] The grating 211 is used to split the laser beam and generate a specific intensity distribution to achieve different functions. Specifically, the grating 211 is an optical element with a periodic structure, usually made of a transparent material (such as glass) or a reflective material, with many parallel slits or grooves etched on it. When the laser beam shines on the grating, according to the principle of light diffraction, the laser beam will diffract in different directions, forming multiple diffracted beams. In the optical drive 20, this property of the grating is used to split a laser beam into a main beam and several auxiliary beams. For example, it is common to split the laser beam into three beams, with the middle one being the main beam and the two on the sides being auxiliary beams. The main beam and auxiliary beams can be used to achieve different functions. For example, in traditional applications, the main beam is usually used to read or write data on an optical disc, while the auxiliary beams are used for other functions, such as focusing and tracking control. In addition to splitting the beam, the grating 211 is also used to separate the incident laser beam from the reflected light and guide the reflected light to the photodetector component 213.

[0065] Objective lens 212 is essentially a lens with a high numerical aperture (NA). It operates based on the principle of light refraction. When a laser beam passes through objective lens 212, the lens refracts the beam, focusing it into a very small and concentrated spot. The size of this spot directly affects the accuracy of data reading and writing by the optical drive. Objective lens 212 minimizes the spot size to form an extremely small spot, thereby improving data reading and writing accuracy. The numerical aperture of the objective lens determines the minimum focused spot size of the laser beam. Generally, the spot diameter is directly proportional to the wavelength of the laser beam and inversely proportional to the NA of the objective lens. That is, the larger the NA, the larger the spot size; the smaller the NA, the smaller the spot size. With a fixed NA, the longer the wavelength of the laser beam, the larger the spot size; the shorter the wavelength, the smaller the spot size.

[0066] The photodetector component 213, typically a photodiode integrated circuit (PDIC), mainly composed of photodiodes, is used to receive the light signal reflected from the optical disc by the laser beam and convert it into an electrical signal. For example, when the laser emitting component 210 emits a laser of a specific wavelength (such as blue or red light) and illuminates the pits and lands on the surface of the optical disc, the pits cause a decrease in laser reflection intensity, while the lands reflect more strongly. When reading data from the optical disc, the photodiodes detect changes in the reflectivity of the reflected light after the beam reaches the recording layer, converting the light signal into an electrical signal (binary 0 / 1). The photodetector component 212 typically includes multiple photodiodes, which are used to detect reflected light of different directions and intensities to obtain data signals, focus error (FE) signals, and tracking error (TE) signals, etc.

[0067] II. Servo System 22.

[0068] The servo system 22 may include a focusing servo 221, a track-following servo 222, a tilting servo 223, and a line-following servo 224.

[0069] The focusing servo 221 is used to control the objective lens 212 to move along the Z-axis (up and down), so that the laser beam can be focused onto different layers of the optical disc 30. Here, the Z-axis refers to the direction perpendicular to the plane of the optical disc.

[0070] The track-seeking servo 222 controls the movement of the objective lens 212 along the radial direction of the optical disc, such as moving it from the inside to the outside or from the outside to the inside, thereby positioning the laser beam onto different tracks. Taking the recording layer as an example, the recording layer includes multiple tracks. When the objective lens 212 moves from the inside to the outside along the radial direction of the recording layer, the laser beam moves from the inner track to the outer track; when the objective lens 212 moves from the outside to the inside along the radial direction of the recording layer, the laser beam moves from the outer track to the inner track. When data at a specific location on the optical disc needs to be accessed, the track-seeking servo is responsible for quickly and accurately moving the laser head to the target track.

[0071] The tilt servo 223 is used to control the (horizontal rotation) angle of the objective lens 212. By adjusting the rotation angle of the objective lens 212, the tilt angle between the laser head 21 (objective lens 212) and the optical disc 30 can be changed.

[0072] The tracking servo 224 controls the laser head 21 to track the spiral track of the optical disc 20, ensuring that the laser beam always reads or writes data along the track, preventing data reading errors or incomplete writing caused by track deviation. Specifically, the tracking servo 224 can control the lateral (horizontal) position of the objective lens 212, so that the laser beam is precisely aligned with the center line of the track. In some descriptions, tracking is also called path following or tracking. Path seeking is also called track finding.

[0073] It should be noted that "track seeking" and "track following" are different concepts. Track seeking refers to the process of the laser head rapidly moving across the surface of the optical disc to locate the target track. This process involves jumping from the current position to the designated track to ensure that the laser head can quickly find the starting position for reading or writing. Track following, on the other hand, refers to the continuous fine-tuning of the laser head's position on the target track to compensate for track offsets caused by optical disc rotational eccentricity, mechanical vibration, or disc deformation, ensuring that the laser beam is always focused on the center line of the track.

[0074] In a specific application scenario, when data needs to be read from a specific location on an optical disc, the track-seeking servo 222 typically moves the laser head 21 quickly to the vicinity of the target track for coarse positioning. Then, the tracking servo 224 takes over, driving the objective lens 212 to move slightly horizontally, ensuring the laser beam is precisely aligned with the track center. During the data reading phase, the tracking servo 224 continuously operates, dynamically compensating for offsets caused by optical disc rotation and mechanical vibration, ensuring the laser beam is always precisely aligned with the track centerline.

[0075] III. Control device 23.

[0076] The control device 23 may include a main controller IC, such as a microcontroller (MCU) or digital signal processor (DSP), which is the "brain" of the optical drive 20. It is responsible for coordinating and controlling the operation of various parts of the optical drive 20, including interface communication with electronic devices (such as computers), data processing and transmission, and control of the laser head 21 and the servo system 22. For example, according to the system's read and write instructions, it precisely controls the emission power, frequency, and pulse width of the laser diode to ensure that information is accurately recorded on the optical disc when writing data and that the laser is stably emitted and the reflected light signal is accurately received when reading data. At the same time, the control device 23 is also responsible for cooperating with other components in the laser head 21, such as the photodetector component 213 and the servo system 22. It adjusts the laser emission state according to the signal fed back by the photodetector component 213, and controls the position and focus of the laser head 21 according to the requirements of the servo system 22, so that the laser beam can be accurately positioned on the designated position of the optical disc to achieve efficient and accurate data read and write operations.

[0077] Figure 3 This is a structural example diagram of the optical disc 30 provided in an embodiment of this application. For example... Figure 3 As shown, optical disc 30 may include multiple recording layers and servo layers.

[0078] The recording layer, also known as the data layer, is the layer that actually stores the data. It contains phase change materials and records data in either a crystalline or amorphous state, relying on a laser beam to physically record the information. When a laser beam strikes the recording layer of the optical disc, it causes a physical or chemical change in the phase change materials that make up the recording layer, altering their state. For example, when a laser beam (with power increased to the burning threshold) strikes the recording layer, the phase change material at the focal point changes from an amorphous state to a crystalline state, typically forming a pit. A crystalline phase change material can represent a type of recorded data, such as "1". An amorphous phase change material in the recording layer can represent the data "0".

[0079] A recording layer typically has multiple tracks ( Figure 3 (The black squares in the image). A track is a data storage path arranged in a specific geometry (usually a spiral or concentric circles) on the recording layer. Each track is a continuous path that can store multiple data blocks. These data blocks are typically represented by "pits" and "bumps," which represent binary data 0 and 1, respectively. The optical drive retrieves the data stored on the track by reading the changes in these pits and bumps. In most optical discs (such as CDs, DVDs, and Blu-ray discs), the tracks are usually arranged in a spiral pattern, extending from the inner circle to the outer circle of the disc. The distance between each track is uniform to ensure that the optical head can accurately read and write data on the designated track.

[0080] The servo layer, also known as the independent boot layer, contains servo information such as address markers for the servo beam to read, ensuring the accuracy of laser head 21 positioning. Servo information is usually pre-written into the servo layer; that is, even an unused optical disc contains servo information within its servo layer. Therefore, optical drives typically only read data from the servo layer and do not write data to it. In this application, the servo layer and multiple recording layers are layered, such as... Figure 3 As shown, the servo layer can be located below multiple recording layers. The tilt detection layer can be used to control the tilt angle of the optical disc. To save on optical disc costs, the servo layer is reused as the tilt detection layer in this embodiment.

[0081] Optionally, the tilt detection layer can also be a separate layer added to the optical disc 30. For example, the optical disc 30 may also include multiple recording layers, servo layers, and tilt detection layers, with the servo layers and tilt detection layers located on different layers within the optical disc 30. In this case, the positional relationship between the multiple recording layers and servo layers is not limited. For ease of description, the following will use... Figure 3 The optical disc 30 structure shown is used as an example for explanation (i.e., the servo layer is used as the tilt detection layer).

[0082] It should be noted that, Figures 1 to 3 These are all illustrative examples; in practical applications, the optical drive 20 may have relative... Figure 2 More or fewer components. In practical applications, optical discs may also have other layers, such as a protective layer, a base layer, etc., which are not limited in this application embodiment.

[0083] The more recording layers an optical disc contains, the thicker it is, and the higher the precision required to control the tilt angle between the laser head 21 and the optical disc 30 (referred to as the optical disc tilt angle). For example, the conventional optical disc with a thickness of 0.1 mm requires a tilt angle precision control of 0.64 degrees (deg). This means that to ensure correct reading or writing of data from the optical disc, the tilt angle must not exceed 0.64 degrees. The optical disc with an independent boot layer provided in this application has a greater number of recording layers than conventional optical discs. The required precision for controlling the tilt angle of the optical disc 30 is increased, such as reaching 0.45 degrees, 0.05 degrees, or 0.02 degrees. Taking a precision requirement of 0.02 degrees as an example, to ensure correct reading or writing of data from the optical disc 30, the tilt angle of the optical disc 30 must not exceed 0.02 degrees, which is 32 times the precision of a conventional optical disc. Existing technology cannot meet the control level precision requirements for this tilt angle, resulting in the inability to accurately read and write data on optical disc 30. This is also a key factor limiting the number of optical disc layers, thus limiting the increase in storage capacity of existing optical discs and preventing their commercial use.

[0084] This application provides a method for controlling the tilt angle of an optical disc 30. This method does not require the addition of a special control component or changes to the original objective lens optical design. It gradually adjusts the tilt angle between the laser head 21 and the optical disc to meet the control accuracy requirements for commercially viable multilayer optical discs through one or more methods.

[0085] The following is applied to Figures 1-3 Taking an example, the control method provided in the embodiments of this application will be described. To keep it concise, reference numerals will be omitted when describing the components in the above figures. For example, the optical drive can be replaced by optical drive 20, the laser head can be replaced by laser head 21, the grating can be replaced by grating 211, the objective lens can be replaced by objective lens 212, the PDIC can be replaced by photoelectric detection component 213, and so on, without further details.

[0086] Figure 4 This is a flowchart illustrating a control method provided in an embodiment of this application. This method can be executed by an optical drive or by a component within the optical drive, such as a control device. The following description uses optical drive execution as an example. The control method provided in this embodiment may include some or all of the following steps in the process, such as... Figure 4 As shown, the process may include:

[0087] Step 401: The optical drive adjusts the tilt angle of the disc using Method 1, that is: based on the tracking error signal TE of the first laser beam, the tilt angle of the disc is adjusted to a first angle. For a detailed implementation of Method 1, please refer to... Figure 5 The method embodiments shown will not be described again here.

[0088] Step 402: The optical drive determines whether the first angle meets the control precision requirements. If not, proceed to step 403. Once the control precision requirements are met, the optical drive can correctly write data to the optical disc.

[0089] Step 403: The optical drive continues to adjust the disc's tilt angle using Method Two, that is, based on the width of the target track track track tracked by the second laser beam, the disc's tilt angle is adjusted from the first angle to the second angle. For a detailed implementation of Method Two, please refer to... Figure 11 The method embodiments shown will not be described again here.

[0090] Step 404: The optical drive determines whether the second angle meets the control precision requirements. If not, proceed to step 405. Once the control precision requirements are met, the optical drive can correctly write data to the optical disc.

[0091] Step 405: The optical drive continues to adjust the disc's tilt angle using Method 3, that is, based on the tracking error signal TE of the two laser beams, the disc's tilt angle is adjusted from the second angle to the third angle. For a detailed implementation of Method 3, please refer to... Figure 14 The method embodiments shown will not be described again here.

[0092] The following sections will provide a detailed introduction to methods one through three.

[0093] Figure 5 This is a flowchart illustrating the control method of Method 1 provided in this application, as shown below. Figure 5 As shown, the method may include:

[0094] Step 501: The optical drive projects a first laser beam onto the servo layer (i.e., tilt detection layer) of the optical disc through the laser head and detects the first reflected light signal.

[0095] Using the tilt detection layer as Figure 3 For example, in the servo layer, see Figure 6 As shown, the first laser beam can be blue light. The optical drive transmits the blue light emitted by the laser head through the multiple recording layers of the optical disc to the servo layer, and detects the light signal reflected back from the optical disc (denoted as the first reflected light signal).

[0096] In traditional applications, the red light (655nm) emitted by the laser head is typically used as a servo beam, illuminating the servo layer and enabling the servo system to control the precise position of the laser head on the optical disc surface. The blue light (405nm) emitted by the laser head is the recording beam, illuminating the recording layer for the actual data writing process. The shorter wavelength of the blue laser allows it to be focused onto a smaller area, resulting in a smaller spot size. This allows for the formation of finer structures (such as pits and bumps) on the recording layer tracks, increasing data storage density. During data writing on the optical disc, the red light controls the laser head position, ensuring the laser beam is focused on the correct track, while the blue light performs the actual data writing operation. This collaborative approach improves the accuracy and efficiency of the writing process, ensuring that data is correctly stored on the optical disc.

[0097] Unlike traditional applications, in this embodiment, the optical drive can use blue light to illuminate the servo layer. Actually, this blue light is not a servo beam, but rather a detection beam used to adjust the disc tilt angle.

[0098] Optionally, the tilt detection layer needs to be set below multiple recording layers.

[0099] Optionally, the tilt detection layer may not be located below multiple recording layers, as long as the depth distance between the tilt detection layer and the upper surface of the optical disc is greater than or equal to a set distance threshold.

[0100] Optionally, the tilt detection layer is located below multiple recording layers, and the depth distance between the tilt detection layer and the upper surface of the optical disc must be greater than or equal to a set distance threshold.

[0101] When the servo layer is used as a tilt detection layer, it must meet the positional requirements of the tilt detection layer. If the servo layer is not used as a tilt detection layer, its position is not limited. For example, the servo layer can be above multiple recording layers, or it can be below multiple recording layers; there are no specific limitations. For ease of description, the following text will use the term "tilt layer". Figure 3 The optical disc structure shown in Figure 30 (which uses the servo layer as the tilt detection layer) will be used as an example for explanation, and will not be described in detail again.

[0102] Step 502: The optical drive focuses the spot of the first laser beam onto the servo layer based on the focus error (FE) signal generated based on the first reflected light signal.

[0103] When an optical drive is working, it needs to precisely focus a laser beam onto the target layer of the optical disc to accurately read data. The FE signal reflects the focusing state of the laser beam on the target layer. When the laser beam is not accurately focused on the target layer, the distribution characteristics of the reflected light (such as the shape and symmetry of the spot) will change. By analyzing the differences in the reflected light, the FE signal can quantify the direction (too close or too far) and degree of defocus. For example, FE>0: The objective lens is too far from the target layer (the focus is below the layer). FE<0: The objective lens is too close to the target layer (the focus is above the layer). FE=0: The focus is accurate (the spot is circular when the focus is accurate. When the focus is too close / too far, the spot is elliptical). Therefore, focus search can be enabled here: the objective lens is moved up and down according to the FE signal of the first reflected light signal to find the optimal focus point of the first laser beam on the servo layer. For example, the specific process of focus search may include: the PDIC generates an FE signal (i.e., the FE signal of the first reflected light signal) based on the first reflected light signal, and the focus servo drives the objective lens to move up and down based on the FE signal until the FE signal of the first reflected light signal approaches 0.

[0104] Optionally, the spot of the first laser beam is focused on the target track of the servo layer.

[0105] Optionally, the number of target orbits is one.

[0106] Optionally, the target track is a specified track in the servo layer, such as the innermost track or the outermost track. Alternatively, the target track can be any track in the servo layer.

[0107] Optionally, the FE signal can be determined by methods such as astigmatism, knife-edge method, and critical angle method, which will not be elaborated here.

[0108] After the first laser beam is focused, the focusing servo is in a focus lock state, ensuring that the first laser beam is always focused on the target track of the servo layer.

[0109] Step 503: The optical drive generates a first tracking error (TE) signal based on the first reflected light signal of the first laser beam in the focused state.

[0110] Here, "being in a focused state" means that the spot of the first laser beam is focused on the servo layer. The PDIC receives the first reflected light signal of the first laser beam and generates a first TE signal based on the first reflected light signal of the focused first laser beam. In other words, the first TE signal is generated by the PDIC based on the light signal reflected by the first laser beam in the focused state of the servo layer.

[0111] There are several methods for generating the first TE signal. For example, in the three-beam method, a grating divides the first laser beam into a main beam and a sub-beam. The difference in intensity of the reflected light from the sub-beam generates the TE signal (TE signal = left sub-beam signal - right sub-beam signal). In differential phase detection (DPD), the TE signal is directly generated by the phase difference of the reflected light from the main beam, without the need for a sub-beam.

[0112] Step 504: The optical drive adjusts the tilt angle between the laser head and the optical disc to a first angle according to the first TE signal, so that the peak-to-peak (Maximum Peak-to-Peak, MPP) of the first TE signal is kept at a first set value.

[0113] Typically, the tilt angle between the laser head and the optical disc cannot be directly measured; instead, it is measured using other detection signals (such as bit error rate, coma aberration, etc.). For example, the larger the tilt angle of the optical disc, the greater the track error, and the higher the bit error rate. When the bit error rate is low, the tilt angle of the optical disc can be considered to have been adjusted to meet the accuracy control requirements.

[0114] In this application, the tilt angle of the optical disc is controlled and measured using the MPP of the first TE signal. For example, step 504 may include: the optical drive adjusting the horizontal angle of the objective lens via a tilt servo, thereby changing the tilt angle between the objective lens (laser head) and the optical disc. That is, the tilt angle of the optical disc is adjusted via the tilt servo. During the adjustment process, the optical drive can adjust the objective lens multiple times according to a set step angle, such as rotating the objective lens by a set angle each time. After the objective lens is adjusted, the new reflected light signal is captured again by the PDIC, generating an updated first TE signal. The optical drive monitors the MPP of the first TE signal during the adjustment process. When the MPP of the first TE signal remains at a first set value, the tilt angle adjustment stops. At this point, the tilt angle of the optical disc has been adjusted to the first angle. Optionally, the set angle can be user-set or a default value. The value of the set angle should not be too large or too small to avoid excessive adjustment leading to reduced accuracy or low adjustment efficiency.

[0115] It should be noted that although the tracking error signal is used here, in Method 1, the first laser beam does not actually track the target trajectory. It is only necessary to keep the spot of the first laser beam focused on the target trajectory of the servo layer.

[0116] After the first laser beam is focused onto the target track of the servo layer, the first TE signal can be detected. The MPP of the first TE signal reflects the alignment degree between the first laser beam and the target track of the servo layer, and can be used to determine whether the laser head has successfully locked onto the target track. After the optical drive locks the focus (e.g., FE≈0), it keeps the first laser beam focused on the target track. Each time the objective lens is adjusted, the first TE signal detected by the PDIC will show an S-curve in each rotation cycle. The MPP value is the difference between the highest value (positive peak value) and the lowest value (negative peak value) of the first TE signal in one cycle, that is, MPP value = positive peak value - negative peak value.

[0117] If the optical drive adjusts the objective lens multiple times, it will produce multiple first TE MPPs. Figure 7 This is a waveform diagram of the first TE signal measured during the process of adjusting the disc tilt angle using Method 1. Each time the optical drive adjusts the tilt angle using Method 1, it can acquire the first TE signal within one cycle and obtain the MPP of the first TE signal for that cycle. In this way, each adjustment can obtain an MPP of the first TE signal, and by gradually adjusting the tilt angle, the change in MPP can be observed. When the MPP of the first TE signal is at a first set value, the optical drive can stop adjusting the tilt angle, keeping the MPP of the first TE signal at the first set value.

[0118] The first setting is determined based on the correlation between the MPP and the tilt angle of the optical disc. Figure 8 The correlation curve between MPP and tilt angle provided for embodiments of this application. Figure 8 As shown, the horizontal axis of the curve represents the tilt angle of the optical disc, and the vertical axis represents the MPP of the first TE signal. Based on experimental data (such as... Figure 7 It can be concluded that the measurement accuracy of MPP is 10%, meaning that the measured value of MPP in the range of 0.9-1 may be inaccurate. In other words, it can be ensured that the maximum tilt angle of the optical disc is adjusted to the tilt angle corresponding to an MPP of 0.9 for the first TE signal. Figure 8 When the MPP is 0.9, the tilt angle of the optical disc is 0.45 degrees.

[0119] As mentioned earlier, the tilt angle of an optical disc cannot be directly measured. Therefore, we use the coma aberration Wc caused by the disc's tilt to characterize the tilt angle θ. The relationship between Wc and the tilt angle θ can be found in [reference needed]. Figure 8 The formula shown will not be repeated here. Among them, Figure 8The curve shown is the measurement data obtained by the technicians of this application under the following parameters: the first laser beam is blue light, the blue light is focused on the servo layer and the track pitch of the servo layer is 0.64um, the height difference between the land and the groove is 68nm, the NA is 0.85, the blue light wavelength is 405nm, and the servo layer depth is 214um.

[0120] from Figure 7 The waveform of any first TE signal within one cycle shows that the positive and negative peak values ​​of the first TE signal are not stable values ​​within each cycle; both fluctuate, with the fluctuation range accounting for approximately 10% of the total amplitude. Therefore, the measurement accuracy of MPP is 10%. In other words, when MPP reaches any value within the range of 0.9 to 1 of the total amplitude, it cannot be determined whether it is 0.9 or 1. Therefore, even if the MPP of the first TE signal is adjusted to its maximum amplitude, it can only guarantee that the tilt angle of the optical disc is adjusted to 0.45 degrees. In reality, when the MPP of the first TE signal is adjusted to its maximum amplitude, the tilt angle of the optical disc may be less than 0.45 degrees.

[0121] When the first setting value is set to the maximum amplitude of the MPP of the first TE signal, that is, the maximum value of the MPP of the first TE signal during the adjustment of the tilt angle, in one mode, the optical drive will control the tilt angle over-adjustment to determine whether the MPP has reached the maximum value, that is, the optical drive adjusts the tilt angle to make the MPP reach the maximum value.

[0122] Optionally, in addition to using blue light as the first laser beam, this application also supports using lasers with other wavelengths as the first laser beam. For example, a laser with a shorter wavelength than blue light can be used in the embodiments of this application, as long as the tilt angle of the optical disc can be adjusted according to the MPP of the TE signal of the laser beam.

[0123] It should be noted that, Figure 8 As an example only, the correlation between MPP and the tilt angle of the optical disc may differ under different parameters (such as different wavelengths of the laser beam).

[0124] Optionally, before step 504 (adjusting the tilt angle of the optical disc according to the first TE signal), the tilt angle and tilt direction of the optical disc can be initially adjusted to an initial angle to significantly reduce the degree of tilt. Then, based on the initial angle, the tilt angle is finely adjusted according to the first TE signal to adjust the tilt angle from the initial angle to a first angle. The initial angle is determined by the user.

[0125] It should be noted that there are two tilt directions for an optical disc: the inner axis direction and the outer axis direction. The inner axis direction refers to the direction from the edge of the disc towards the center. The outer axis direction refers to the direction from the center of the disc towards the edge. For ease of representation, "+" will be used to represent the outer axis direction and "-" to represent the inner axis direction. Therefore, initial values ​​could be, for example, +0.64 degrees (abbreviated as deg), +0.70 degrees, +0.80 degrees, -0.64 degrees, -0.70 degrees, or -0.80 degrees, etc.

[0126] The process of controlling the tilt angle and tilt direction of the optical disc to the initial angle can be referred to the process of controlling the optical disc tilt with a target of +0.64deg in the "BD RE - Physical Format Specification". For the sake of brevity, it will not be described in detail here.

[0127] In practical applications, when initially controlling the tilt angle and direction of an optical disc to the initial angle, it's possible to control only the tilt angle without specifying the tilt direction. This is because, with a fixed tilt angle, the effect is the same whether the disc tilts inwards or outwards; therefore, it's sufficient to focus on whether the tilt angle meets the control requirements. For example, the tilt angle can be controlled to 0.64 degrees, without specifying whether it's +0.64 degrees or -0.64 degrees.

[0128] The above-described scheme, which involves first roughly adjusting the tilt of the optical disc and then fine-tuning it subsequently, effectively improves control efficiency, simplifies control operations, and enhances control precision. This scheme quickly adjusts the disc's tilt to a suitable range, saving time and avoiding excessive time spent on overly fine-tuning in the initial stages, thus improving overall control efficiency. The rough adjustment lays the foundation for subsequent fine-tuning, allowing it to be performed closer to the ideal state, thereby improving the final control precision.

[0129] Step 505 (Step 402): The optical drive determines whether the first angle meets the accuracy requirement. If it does, a write operation can be performed on the optical disc; otherwise, it jumps to step 1101 to execute the control method flow of mode two (see...). Figure 11 ).

[0130] The tilt angle measures the degree of tilt of the optical disc, which introduces track errors. See also Figure 9 As shown, Figure 9This diagram illustrates a write operation based on a recording beam (e.g., blue light) and a servo beam (e.g., red light). The optical drive projects and focuses red light through multiple recording layers onto the servo layer, and projects and focuses blue light onto the target recording layer. When the optical disc is not tilted, i.e., the tilt angle is 0, the optical axis of the red light emitted by the optical drive on the servo layer is aligned with the optical axis of the blue light emitted by the optical drive on the target recording layer. Thus, when the focal point of the blue light on the target track of the target recording layer and the focal point (servo spot) of the red light on the target track of the target recording layer are aligned, no track error occurs.

[0131] See Figure 10 As shown, when an optical disc is tilted, the focal points of the red and blue light become offset on the disc surface. This means the optical axis of the red light emitted by the drive on the servo layer is not aligned with the optical axis of the blue light emitted by the drive on the target recording layer, thus causing track errors. Figure 10 It can be seen that the conversion formula between the tilt of the optical disc and the track error is:

[0132] Δs=d×tanθ

[0133] Where Δs represents the value and direction of the track error, d represents the vertical distance between the target recording layer and the servo layer, θ represents the tilt angle and direction of the optical disc, which are also the tilt angle and direction of the servo layer, and tan() represents the tangent function. From the formula, it can be seen that when the optical disc is tilted, d is fixed, the larger θ is, the larger the value of tanθ is, and the larger Δs (track error) is.

[0134] For example, suppose the tilt angle θ of the optical disc is +0.64deg. Select the recording layer furthest from the servo layer as the target recording layer. Assuming the vertical distance between the target recording layer and the servo layer is 165 micrometers (µm), the track error is: Δs = d × tanθ = 165 × tan(+0.64) = +1.843 (µm) = +1843 (nm). Assuming the width of a track is 320 nanometers (nm), the track error is measured by the number of tracks. In this case, the track error is: (+1843) ÷ 320 = +5.8 (tracks).

[0135] It should be noted that adjusting the tilt angle of the optical disc does not aim to completely eliminate track errors. Theoretically, the laser head should be parallel to the optical disc plane, i.e., the tilt angle should be 0, and the track error should be 0, to ensure the laser beam is precisely focused on the target track of the target recording layer. However, due to manufacturing tolerances, the width of the track itself, and the entanglement capabilities of the software, perfect parallelism is not necessary; a certain range of tilt angles (or a certain range of track errors) is allowed, but the tilt angle must meet the tilt control accuracy requirements. The tilt control accuracy requirements of the optical disc are related to many factors such as laser wavelength, objective lens numerical aperture (NA), optical disc thickness, optical disc refractive index, and error-correcting code (ECC). For example, the greater the optical disc thickness, the higher the tilt angle control accuracy requirement. This application does not limit the specific value of the optical disc tilt angle control accuracy requirement in its embodiments.

[0136] In some embodiments, the tilt control accuracy of the optical disc is required to be greater than or equal to 0.45 degrees. As mentioned above, Method 1 can adjust the first angle to 0.45 degrees or even lower. In this case, the first angle usually meets the tilt control accuracy requirements of the optical disc and no further adjustment is needed. Normal read and write operations can be performed on the optical disc.

[0137] In other embodiments, the optical disc tilt control accuracy requirement is less than 0.45 degrees, for example, 0.02 degrees. As mentioned earlier, there is a possibility that the first angle is less than or equal to 0.02 degrees, which satisfies the optical disc tilt control accuracy requirement, and normal read and write operations can then be performed on the optical disc. If the first angle is greater than 0.02 degrees, then mode two can be enabled (see...). Figure 11 Continue to adjust the tilt angle to meet the precision requirements for optical disc tilt control.

[0138] Alternatively, in an alternative approach, the optical drive can use a push-pull signal of the first reflected light signal to control the tilt angle of the optical disc, or it can use an radio frequency (RF) signal of the first reflected light signal to control the tilt angle of the optical disc. The push-pull signal is used to generate the first TE signal. Therefore, the optical drive can also use the push-pull signal to represent the first TE signal, and further determine the relationship between the push-pull signal and the tilt angle, thereby achieving the same effect as using the first TE signal to control the tilt angle of the optical disc. The RF signal is the original high-frequency signal of the first reflected light signal reflected from the optical disc by the first laser beam, including the encoded information of data pits and lands in the target track on the servo layer. The measurement accuracy of these two signals can achieve the same effect as the first TE signal.

[0139] One method uses the MPP of the first TE signal to control the tilt angle of the optical disc. Through experimental simulation, the engineers of this application have found that the track width can be equivalent to the MPP of the first TE signal, but the measurement accuracy of the track width can be improved to 1%. As mentioned earlier, the measurement accuracy of MPP is 10%, and the measurement accuracy of track width is 10 times that of MPP. Measurement accuracy can also be understood as the precision of controlling the tilt angle of the optical disc. Combined with... Figure 8 Simulation data shows that if the measurement accuracy of MPP can reach 1%, the control accuracy of the optical disc tilt angle can reach 0.05 deg, which is about 10 times higher than that of Blu-ray. Based on this, this application provides a second tilt control method, namely: controlling the tilt angle of the optical disc based on the track width of the target track.

[0140] Figure 11 This is a flowchart illustrating the control method of Method Two provided in this application, as shown below. Figure 11 As shown, the method may include:

[0141] Step 1101: The optical drive controls the laser head through the tracking servo to make the first laser beam track (follow) the target track on the servo layer.

[0142] In Method 1, the optical drive focuses the first laser beam onto the fixed target track on the servo layer. As the disc rotates, the optical drive uses a tracking servo to control the laser head to move laterally (horizontally), ensuring that the first laser beam is always aligned with the center line of the target track on the servo layer. This can be understood as the optical drive reading data from the target track on the servo layer using the first laser beam.

[0143] See Figure 12 , Figure 12 This diagram illustrates a control method for tracking a target trajectory using a first laser beam via a tracking servo control, as provided in an embodiment of this application. In this method, the controlled object is the lateral movement of an objective lens. The input signal to the tracking servo controller can be the deviation between a given position (the target position of the objective lens) and a measured position (the actual position after movement). The tracking servo controller determines the position error e(t) = r(t) - y(t) based on the deviation between the given position and the actual measured position, where r(t) is the setpoint and y(t) is the feedback value. The tracking servo controller generates and outputs a control signal (C(s)) based on the position error, dynamically adjusting the lateral movement of the objective lens to correct the laser beam position. The adjusted actual measured position of the objective lens serves as the feedback signal to form a closed loop.

[0144] In specific implementation, the position error can be the first TE signal of the first laser beam. The PDIC outputs the first TE signal in real time and uses it as an input signal to the controller of the tracking servo. The controller continuously adjusts to counteract interference such as track eccentricity and vibration, so that the first laser beam emitted by the laser head controlled by the optical drive is always aligned with the target track when tracking the target track.

[0145] Step 1102: The optical drive detects the track pitch of the target track track tracked by the first laser beam.

[0146] Step 1103: The optical drive adjusts the tilt angle between the laser head and the optical disc from a first angle to a second angle based on the track width of the detected target track, so that the track width of the detected target track remains at the second set value.

[0147] Based on the experimental simulation data from the embodiments of this application, it can be concluded that the width of the detected target track is directly proportional to the tilt angle of the optical disc. Within a certain range, for the same track, the smaller the width of the detected target track, the smaller the tilt angle of the optical disc. Therefore, in step 1103, the optical drive can adjust the tilt angle of the optical disc through a tilt servo and monitor the width of the target track detected during the adjustment process. Based on the width of the detected target track, the tilt angle of the optical disc is adjusted from a first angle to a second angle. The second angle is smaller than the first angle; for example, the first angle is 0.45 degrees and the second angle is 0.05 degrees.

[0148] There is a correlation between the track width of the target track and the servo loop gain of the tracking servo. For example, the width of the detected target track is proportional to the servo loop gain. In one implementation, the optical drive acquires the servo loop gain and uses it to represent the track width of the detected target track, and then adjusts the tilt angle of the optical disc based on the acquired servo loop gain.

[0149] Please see Figure 13 , Figure 13 This is a schematic diagram illustrating the relationship between servo loop gain and optical disc tilt angle, provided in an embodiment of this application. Figure 13 The list shows the tilt angle range corresponding to the servo loop gain range of 0.96 to 1.03, which is -0.3deg to 0 and 0 to +0.3deg. Figure 13 This displays multiple measurement data points, with each continuous curve representing one measurement. Figure 13It can be seen that the maximum error of these multiple measurements is within the servo loop gain range of 0.97 to 0.98 corresponding to a tilt angle of 0.05 degrees. This can be understood as the disc tilt angle potentially being 0.05 degrees when the measured servo loop gain is between 0.97 and 0.98. Therefore, the measurement accuracy of the servo loop gain is 0.98 - 0.97 = 0.01 (1%). Thus, conservatively estimating the tilt angle adjustment based on the servo loop gain, the optical drive can be adjusted to 0.05 degrees. The actual tilt angle is smallest (e.g., 0) when the servo loop gain reaches its maximum value (e.g., 0). However, due to the measurement accuracy of 0.01, it cannot be guaranteed that the tilt angle can be adjusted to 0 at 0.96, but it can be guaranteed that the tilt angle will be at least 0.05 degrees when the servo loop gain reaches its maximum value.

[0150] Therefore, after keeping the first laser beam focused and tracking the target track, when the optical drive adjusts the tilt angle of the optical disc via the servo loop gain, it is similar to the adjustment method in Method 1. Each time, the optical drive rotates the objective lens by a set angle via the tilt servo. After adjustment, the optical drive adjusts the tracking offset of the first laser beam via the tracking servo, so that the first laser beam is aligned with the target track of the servo layer. The servo loop gain is monitored throughout the entire tilt angle adjustment process. When the servo loop gain reaches the third set value, the tilt angle adjustment stops, and the tilt angle of the optical disc at this point is recorded as the second angle. The third set value can be the maximum amplitude of the servo loop gain, such as in... Figure 13 In this configuration, the maximum amplitude of the servo loop gain is 0.96, thereby maximally reducing the tilt angle of the optical disc. At this point, the second angle is equal to or less than 0.05 degrees. It can be understood that when the detected servo loop gain is the third set value, the track width of the detected target track is the second set value.

[0151] It should be noted that the angle set in Method 2 can be different from the angle set in Method 1. Theoretically, the angle set in Method 2 should be smaller than the angle set in Method 1 to achieve fine-tuning.

[0152] The following describes how to determine the servo loop gain, combined with... Figure 12 As can be seen, the servo loop gain can be determined based on the servo loop transfer function, and the servo loop gain satisfies the following formula:

[0153] Servo loop gain=∣Servo loop(s)∣

[0154] Servo loop(s) is the servo loop transfer function, which satisfies the following formula:

[0155] Servo loop(s) = C(s)·P(s);

[0156] In this context, C(s) is the transfer function of the controller, responsible for generating control signals (such as voltage or current) based on the position error e(t). As mentioned earlier, the input to C(s) is the position error (the deviation between the target position and the actual position). The output is the control signal (e.g., the voltage driving the tracking servo motor). P(s) is the transfer function of the controlled object (here, the tracking servo motor), used to describe the dynamic response from the control signal to the actual position change. The input to P(s) is the control signal. The output is the actual position (e.g., the rotation angle of the tracking servo motor). The rotation of the tracking servo motor can be accompanied by a horizontal rotation of the astrolabe.

[0157] Besides servo loop gain, optical drives can also determine track width based on laser diffraction. Laser diffraction utilizes the periodic structure of the track to diffract the laser beam, and the track width is calculated from the diffraction angle. The relationship between the diffraction angle and the track width satisfies the following formula:

[0158]

[0159] Where d represents the orbital spacing; λ represents the laser wavelength (e.g., 405nm for blue light); and θ is the first-order diffraction angle.

[0160] Alternatively, the optical drive can also determine the track width by microscopic imaging or other optical signal measurement methods, which is not limited in this application embodiment.

[0161] Since the track width is proportional to the servo loop gain, the relationship between the track width and the tilt angle can be referenced. Figure 13 Examples.

[0162] Optionally, there can be only one target track. This target track can be any track on the servo layer, such as the target track on the servo layer where the optical drive focuses the spot of the first laser beam using method one. This eliminates the need to refocus the first laser beam onto other tracks on the servo layer, improving adjustment efficiency.

[0163] Optionally, there can be multiple target tracks. The optical drive tracks the first laser beam onto multiple tracks of the servo layer, and then adjusts the tilt angle of the optical disc based on the track width detected for each track track tracked by the first laser beam. The adjustment method for each track is the same, so the optical drive can adjust the tilt angle of the optical disc multiple times. The tilt angle after each adjustment may be different or the same. For example, if there are two target tracks, namely track 1 and track 2, the optical drive first tracks the first laser beam onto track 1 and detects the track width of track 1. Then, it adjusts the tilt angle of the optical disc according to the track width of track 1 (such as servo ring gain) to keep the servo ring gain at the third set value. At this time, the tilt angle of the optical disc may be 0.05 degrees. Then, the optical drive positions the first laser beam near track 2 using a track-seeking servo. It then uses a focusing servo and a tracking servo to make the first laser beam track track 2 and detects the track width of track 2. Based on the track width of track 2 (such as servo loop gain), the optical disc tilt angle is adjusted to keep the servo loop gain at the third set value. At this time, the optical disc tilt angle may still be 0.05 degrees or 0.02 degrees, etc., which are lower than 0.05 degrees.

[0164] In Method 2, the first laser beam can be the same as the first laser beam in Method 1 (blue light), i.e., the first laser beam used in Method 1 can be used. Optionally, Method 2 can also use other laser beams; for example, the first laser beam in Method 2 can also be red light.

[0165] Step 1104 (Step 404): The optical drive determines whether the second angle meets the precision control requirements. If it does, a write operation can be performed on the optical disc; otherwise, it jumps to step 1401 to execute the control method flow of mode three (see...). Figure 14 ).

[0166] In some embodiments, the tilt control accuracy of the optical disc is required to be greater than or equal to 0.05 degrees. As mentioned above, Method 2 can adjust the tilt angle of the optical disc to 0.05 degrees or even lower. In this case, the second angle can usually meet the tilt control accuracy requirements of the optical disc, and no further adjustment is required. The optical drive can perform normal read and write operations on the optical disc.

[0167] In some embodiments, the optical disc tilt control accuracy requirement is less than 0.05 degrees, for example, 0.02 degrees. As mentioned above, in one possible case, the second angle is less than or equal to 0.02 degrees, which meets the optical disc tilt control accuracy requirement, and the optical drive can then perform normal read and write operations on the optical disc. In another possible case, the second angle is greater than 0.02 degrees, and the optical drive can enable mode three (see...). Figure 14 This eliminates track errors caused by residual tilt angles, thereby achieving the desired precision in optical disc tilt control.

[0168] Figure 14 This is a flowchart illustrating the control method of Method 3 provided in this application, as shown below. Figure 14 As shown, the method may include:

[0169] Step 1401: The optical drive projects the second laser beam (recording beam, such as blue light) emitted by the laser head onto the target recording layer of the optical disc, and projects the third laser beam (servo beam, such as red light) emitted by the laser head onto the servo layer of the optical disc. The target data is written onto the target track of the target recording layer through the main spot of the second laser beam.

[0170] Currently, when writing to optical discs, the recording beam is typically blue light. As mentioned earlier, the high energy of blue light allows it to effectively change the state of the recording layer material, enabling data writing. Furthermore, the shorter wavelength of blue laser light (approximately 405 nanometers) allows it to be focused onto a smaller area, thereby increasing data storage density.

[0171] Here, the optical drive can split the second laser beam into a main beam and an auxiliary beam using a grating. When the optical drive writes data onto the optical disc, the blue light emitted by the drive produces a main spot and a sub-spot when passing through the same objective lens. The main spot is the spot formed by the main blue light beam being focused by the objective lens, illuminating the recording layer of the disc and forming the primary spot area. It has a small diameter and high power. The sub-spot is the secondary spot area formed by the auxiliary blue light beam passing through the objective lens, located around the main spot. It has a larger diameter and lower power. In traditional applications, the main spot is typically used for reading and writing data on the recording layer. The sub-spot is not used for reading and writing data but provides additional information to assist the main spot in reading and writing data, helping to improve the stability and accuracy of the read / write process. Unlike traditional applications, this solution uses the main spot to write data on the target recording layer and the sub-spot to read data. The specific execution process can be seen in step 1402 below.

[0172] The optical drive emits a third laser beam (such as red light) that penetrates the target recording layer and illuminates the servo layer. The red light spot is focused on the servo layer, and the blue light main spot is controlled by the tracking servo to write the target signal on the target track of the target recording layer.

[0173] Optionally, the target recording layer can be any recording layer on the optical disc.

[0174] Optionally, the target recording layer is the recording layer furthest from the servo layer in the optical disc. This implementation can solve both the alignment problem when the optical head reads and writes data, and the problem of correcting coma at the deepest part of the optical disc.

[0175] Optionally, the target data can be a known set of data.

[0176] Optionally, the target data may include servo signals read through the servo red light spot, such as track position information.

[0177] Optionally, the target data may also include target signals, which may be media process platform (MPP) signals or radio frequency (RF) signals, etc.

[0178] Optionally, the blue light master spot writes target data of a specified length into the target track of the target recording layer. The specified length is determined by the user.

[0179] Optionally, there can be one or more target tracks. Multiple target tracks indicate that the optical drive controls the blue light master spot to write target data onto multiple tracks of the target recording layer. The target data written on different tracks can be the same or different.

[0180] Optionally, the blue light master spot writes a ring of target data onto the target track in the target recording layer. This makes it easier to read the target data during subsequent step 1402, speeding up the tilt adjustment of the optical disc.

[0181] Optionally, before the optical disc is used, the main blue light spot writes a ring of target signal onto the target track in the target recording layer. This ensures that the recording layer of the optical disc contains only target data and no other data, making it easier to identify the target data during subsequent steps 1402.

[0182] Optionally, the number of secondary light spots is two or more.

[0183] When the target recording layer is the recording layer furthest from the servo layer in the optical disc, and the target track is the middle track within the target recording layer, the scenario where the main spot writes a ring of target signal on the target track in the target recording layer can be seen in [reference needed]. Figure 15A and Figure 15B .

[0184] See Figure 15A , Figure 15A This is a schematic diagram illustrating a scenario where the blue light is written to the target signal when the tilt angle of an optical disc is 0, as provided in an embodiment of this application. Figure 15AAs shown, the blue light emitted by the optical drive forms a primary and secondary spot on the target recording layer. The red light emitted by the optical drive penetrates the target recording layer and illuminates the servo layer, where the red light spot is focused. In a scenario where a target signal is written onto a user-specified track (i.e., the target track), when the disc is not tilted (i.e., the tilt angle is 0), the optical axis of the red light emitted by the optical drive on the servo layer is aligned with the optical axis of the blue light emitted by the optical drive on the target recording layer. Therefore, the primary blue light spot accurately aligns with the target track in the target recording layer when it reaches the target recording layer (see...). Figure 15A (The "■" in the text).

[0185] See Figure 15B , Figure 15B This is a schematic diagram illustrating a scenario where the tilt angle of an optical disc is not 0, as provided in an embodiment of this application, during the writing of the target signal to the blue light. Figure 15B As shown, when an optical disc with a servo layer is tilted (i.e., the tilt angle is not zero), the optical axis of the red light emitted by the optical drive on the servo layer is not aligned with the optical axis of the blue light emitted by the optical drive on the target recording layer. Therefore, when the blue light master spot reaches the target recording layer, it cannot be accurately aligned with the target track in the target recording layer, resulting in the blue light master spot actually aligning with the track (see...). Figure 15B (▲ in the text) and the target orbit (see Figure 15B There is a track error (TE) between the "■" in the figure.

[0186] Although Figure 15B Only one scenario of a tilted disc is shown, but through... Figure 15A and Figure 15B It can be seen that the greater the tilt angle of the optical disc, the greater the deviation between the optical axis of the red light emitted by the optical drive on the servo layer and the optical axis of the blue light emitted by the optical drive on the target recording layer. This will result in a greater track error between the actual track written by the laser beam and the target track.

[0187] It should be understood that in step 1401, due to the presence of a second angle (e.g., 0.05 degrees), the optical axes of the red and blue light may be slightly offset, resulting in a trajectory error of 0.05 degrees. This application can eliminate this residual trajectory error through the following steps.

[0188] Step 1402: The optical drive reads the data on the target track of the target recording layer through the target sub-spot of the second laser beam.

[0189] from Figure 15BAs can be seen, the secondary blue light spot is around the primary blue light spot. After the optical drive writes target data on the target track of the target recording layer through the primary blue light spot, the optical drive controls the objective lens to move through the track-seeking servo, so that the primary blue light spot moves to the target track. At the same time, the primary blue light spot will also move to the new track. Optionally, the primary blue light spot can continue to write target data on the new track.

[0190] Combination Figure 15B To understand, if the light source moves from the outside in along the radius of the optical disc, the target sub-spot is blue light sub-spot 2 (sub-spot #2). If the light source moves from the inside out along the radius of the optical disc, the target sub-spot is blue light sub-spot 1 (sub-spot #1). The optical drive uses a servo system to focus the target sub-spot and track it on the target track, thereby reading the target data written within the target track.

[0191] Optionally, there are two blue light sub-spots. The target sub-spot is selected from multiple blue light sub-spots based on the TE signal. For example, the blue light sub-spot with better TE signal quality can be used as the target sub-spot.

[0192] Step 1403: The optical drive detects the reflected light signal of the target sub-spot of the second laser beam (denoted as the second reflected light signal) and generates a second tracking error (TE) signal based on the second reflected light signal; and the optical drive detects the reflected light signal of the servo red light (denoted as the third reflected light signal) and generates a third tracking error (TE) signal based on the third reflected light.

[0193] Step 1404: The optical drive adjusts the tilt angle between the laser head and the optical disc from the second angle to the third angle based on the second TE signal and the third TE signal.

[0194] Step 1404 may include:

[0195] Step 1404-1: Fine-tune the position of the objective lens using the optical drive, and monitor the second TE signal of the target sub-spot and the third TE signal of the servo red light after adjustment.

[0196] For example, in one implementation, the optical drive adjusts the lateral (horizontal) movement of the objective lens via a tracking servo. For instance, each adjustment moves the objective lens by a set step size, typically a small movement. After the movement, the PDIC detects the second reflected light signal from the target sub-spot and generates a new second TE signal. Similarly, the PDIC detects the third reflected light signal from the servo red light and generates a new third TE signal. This allows the acquisition of the time-domain waveforms of the second and third TE signals before and after the objective lens movement.

[0197] Optionally, users can simultaneously observe the time-domain waveforms of the second TE signal and the third TE signal using visualization tools (such as an oscilloscope).

[0198] Step 1404-2: When the time-domain waveforms of the second TE signal and the third TE signal are synchronized, stop adjusting the position of the objective lens. At this time, the tilt angle between the laser head and the optical disc is the third angle.

[0199] There are various types of waveform synchronization, and different visualization tools may exhibit different synchronization behaviors. For example, see... Figure 16 As shown, Figure 16 (a) illustrates the waveform synchronization of the second TE signal and the third TE signal, including the overlap of the rising edges of the second TE signal waveform and the third TE signal waveform. The period of one second TE signal may include the periods of one or more third TE signals, without specific limitation. For example, Figure 16 In this example, the period length of the second TE signal is T1, and the period length of the third TE signal is T2, where T2 = 2 × T3. In other possible embodiments, T2 = n × T3, where n is a positive integer.

[0200] Figure 16 (b) shows the asynchronous waveforms of the second TE signal and the third TE signal, where the rising edges of the second TE signal waveform and the third TE signal waveform do not coincide.

[0201] Figure 17 The time-domain waveforms of the second and third TE signals synchronously acquired during tracking of the blue light sub-spot and the servo red light are shown below. Figure 17 It can be seen that the waveform synchronization between the two is manifested in the overlap of the time-domain waveforms of the second TE signal and the third TE signal.

[0202] When the time-domain waveforms of the second and third TE signals are synchronized, the red and blue lights are coaxial. At this point, the required control precision for commercial tilt angles can be achieved.

[0203] The third angle is less than the second angle, and the third angle can be 0.02 degrees.

[0204] Through the above design, the tilt angle of the optical disc is gradually adjusted to meet the precision control requirements through various methods, satisfying the commercial requirements of optical discs with servo layers and multiple recording layers.

[0205] It should be noted that, Figure 4This is only one possible implementation. In other embodiments, methods one, two, and three can be executed independently or in combination. For example, only method one can be used to adjust the tilt angle. Alternatively, only method two can be used to adjust the tilt angle. Or, only method three can be used to adjust the tilt angle. For another example, methods one and two can be used to adjust the tilt angle (as in steps 401-404). Alternatively, methods two and three can be used to adjust the tilt angle (as in steps 403-405). For yet another example, methods one and three can be used to adjust the tilt angle. No specific limitations are imposed.

[0206] Once the tilt angle of the optical disc is controlled to meet the control accuracy requirements through one or more of the above methods, normal read and write operations can be performed on the optical disc. This application provides a data writing method for an optical disc 30. This method is executed by an optical drive or a component of the optical drive (such as a control device). Taking the optical drive as an example, the method may include: the optical drive projecting blue light emitted from a laser head onto a target track of the target recording layer, writing target data on the target track through the main blue light spot, and projecting red light emitted from the laser head onto the servo layer to read servo signals (such as track position information). The target data includes the read servo signals and the data to be stored.

[0207] This application embodiment also provides a method for reading data from an optical disc 30. This method is executed by an optical drive or a component of the optical drive (such as a control device). Taking the optical drive as an example, the method may include: the optical drive projecting blue light emitted from a laser head onto a target track of the target recording layer, and reading data from the target track using the blue light. It should be noted that, unlike traditional data reading methods, when the optical drive reads data from the optical disc, it does not require servo red light to track to the servo layer; data reading can be achieved using only blue light. This is because when writing data, the target data written to the target track by the main blue light spot includes servo signals (such as track position information). Therefore, when reading data from the optical disc, the position of the target track can be directly determined using the servo signals in the read target data.

[0208] The methods provided by the embodiments of this application have been described above with reference to the accompanying drawings. The apparatus provided by the embodiments of this application will be described below with reference to the accompanying drawings.

[0209] Based on the same inventive concept as the method embodiments, this application also provides a control device for performing the above-described... Figure 4 , Figure 5 , Figure 11 , Figure 14 The method executed by the optical drive in the embodiment. For example... Figure 18 As shown, the device 1800 includes a control module 1801, an acquisition module 1802, and an adjustment module 1803. Specifically, in this device 1800, the modules are connected to each other through a communication channel.

[0210] Control module 1801 is used to control the laser head to project a first laser beam onto the tilt detection layer of the optical disc, and to detect a first reflected light signal through a photoelectric detection component; wherein, the first reflected light signal is the light signal of the first laser beam reflected by the tilt detection layer; see details below. Figure 5 The description of step 501 in the method embodiment will not be repeated here.

[0211] Acquisition module 1802 is used to acquire the first tracking error TE signal generated by the photoelectric detection component based on the first reflected light signal; see details below. Figure 5 The description of step 503 in the method embodiment will not be repeated here.

[0212] The adjustment module 1803 is used to adjust the tilt angle between the laser head and the optical disc to a first angle via servo system control, based on the first TE signal, so that the peak-to-peak value (MMP) of the first TE signal remains at a first set value. See details [link to relevant documentation]. Figure 5 The description of step 504 in the method embodiment will not be repeated here.

[0213] In an optional design, the control module 1901 is further configured to: control the laser head via a servo system, causing the first laser beam to track the target track of the tilted detection layer, and to detect the width of the target track; see details below. Figure 11 The descriptions of steps 1101 and 1102 in the method embodiment will not be repeated here.

[0214] The acquisition module 1802 is further configured to, based on the detected width of the target track, control the tilt angle between the laser head and the optical disc from a first angle to a second angle via a servo system, so that the detected width of the target track remains at a second set value; the second angle is smaller than the first angle. See details [link to details]. Figure 11 The description of step 1103 in the method embodiment will not be repeated here.

[0215] In an optional design, the control module 1801 is further configured to: control the laser head to project a second laser beam onto the target recording layer of the optical disc, and detect a second reflected light signal via a photoelectric detection component; the second reflected light signal is the light signal of the second laser beam reflected by the target recording layer; project a third laser beam onto the tilt detection layer of the optical disc via the laser head, and detect a third reflected light signal; the third reflected light signal is the light signal of the third laser beam reflected by the tilt detection layer; see details below. Figure 14 The description of step 1401 in the method embodiment will not be repeated here.

[0216] The acquisition module 1802 is further configured to acquire the second tracking error TE signal generated by the photoelectric detection component based on the second reflected light signal; and the photoelectric detection component to generate a third tracking error TE signal based on the third reflected light signal; see details below. Figure 14 The description of step 1403 in the method embodiment will not be repeated here.

[0217] The adjustment module 1803 is further configured to, based on the second TE signal and the third TE signal, control the tilt angle between the laser head and the optical disc via a servo system to adjust from the second angle to the third angle, so as to synchronize the time-domain waveforms of the second TE signal and the third TE signal; the third angle is smaller than the second angle. See details [link to details]. Figure 14 The description of step 1404 in the method embodiment will not be repeated here.

[0218] This application also provides a control device 1900. For example... Figure 19 As shown, the control device 1900 includes a control circuit 1901 and a power supply system 1902. The control circuit 1901 and the power supply system 1902 can be connected via a bus (such as a power bus). The power supply system 1902 is used to supply power to the control circuit 1901; the control circuit 1901 is used to perform the above-described... Figure 4 , Figure 5 , Figure 11 , Figure 14 The control method executed by the optical drive in this embodiment. The control device 1900 can be used as... Figure 2 The control device 23 and control circuit 1901 can be the above-mentioned Figure 2 The main control chip in the control device 23.

[0219] This application also provides a control system, including a control device and a laser head, wherein the control device is used to perform the above... Figure 4 , Figure 5 , Figure 11 , Figure 14 The embodiment describes a control method executed by the optical drive; the laser head is used to emit a laser beam. The control device can be... Figure 2 The control device 23 in the middle. The laser head can be Figure 2 Laser head 21 in the middle.

[0220] This application also provides an optical storage system, including a control system and an optical disc; the control system is used to perform the above... Figure 4 , Figure 5 , Figure 11 , Figure 14 The embodiment describes the control method executed by the optical drive; the optical disc is used to store data. The control system can be... Figure 2 The optical drive in the middle is 20.

[0221] Based on the above embodiments, this application also provides a computer program that, when run on a computer, causes the computer to perform the above-described actions. Figure 4 , Figure 5 , Figure 11 , Figure 14 The control method provided in the embodiment.

[0222] Based on the above embodiments, this application also provides a computer-readable storage medium storing a computer program, which, when executed by a computer, causes the computer to perform the above-described actions. Figure 4 , Figure 5 , Figure 11 , Figure 14 The control method provided in the embodiments. The storage medium can be any available medium that can be accessed by a computer. For example, but not limited to, a computer-readable medium can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer.

[0223] Based on the above embodiments, this application also provides a chip, which is used to read a computer program stored in a memory and implement... Figure 4 , Figure 5 , Figure 11 , Figure 14 The control method provided in the embodiment.

[0224] Based on the above embodiments, this application provides a chip system including a processor for supporting computer devices to implement... Figure 4 , Figure 5 , Figure 11 , Figure 14 The control method provided in the embodiments. In one possible design, the chip system further includes a memory for storing programs and data necessary for the computer device. The chip system may consist of chips or may include chips and other discrete components.

[0225] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0226] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0227] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0228] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0229] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of protection of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A control method, characterized in that, The method is applied to an optical drive, and the method includes: A first laser beam is projected onto the tilt detection layer of the optical disc by a laser head, and a first reflected light signal is detected; wherein, the first reflected light signal is the light signal of the first laser beam reflected by the tilt detection layer. A first tracking error TE signal is generated based on the first reflected light signal; Based on the first TE signal, the tilt angle between the laser head and the optical disc is adjusted to a first angle so that the peak-to-peak value (MMP) of the first TE signal remains at a first set value.

2. The method as described in claim 1, characterized in that, The step of adjusting the tilt angle between the laser head and the optical disc to a first angle based on the first TE signal includes: Adjust the tilt angle between the laser head and the optical disc; During the monitoring and adjustment process, the MPP of the first TE signal is monitored until the MPP of the first TE signal remains at the first set value, at which point the adjustment of the tilt angle is stopped; wherein, when the adjustment of the tilt angle is stopped, the tilt angle between the laser head and the optical disc is the first angle.

3. The method as described in claim 1 or 2, characterized in that, The method further includes: The laser head is controlled by a servo system to make the first laser beam track the target track of the tilted detection layer and detect the width of the target track; Based on the detected width of the target track, the tilt angle between the laser head and the optical disc is adjusted from the first angle to the second angle, so that the detected width of the target track remains at a second set value; the second angle is smaller than the first angle.

4. The method as described in claim 3, characterized in that, The width of the target track is correlated with the servo loop gain of the servo system; adjusting the tilt angle between the laser head and the optical disc from the first angle to the second angle based on the width of the target track includes: Adjust the tilt angle between the laser head and the optical disc, and control the first laser beam to keep it following the target track of the tilt detection layer through the servo system; During the monitoring and adjustment process, the servo loop gain of the servo system is monitored until the servo loop gain reaches a third set value, at which point the adjustment of the tilt angle is stopped; wherein, when the servo loop gain is the third set value, the width of the target track is the second set value; when the adjustment of the tilt angle is stopped, the tilt angle between the laser head and the optical disc is the second angle.

5. The method as described in claim 4, characterized in that, The servo loop gain of the cyclic servo during the monitoring and adjustment process includes: During the process of adjusting the tilt angle between the laser head and the optical disc, control information of the servo system and position information of the laser head are collected. The servo loop gain of the servo system is determined based on the control information and the position information.

6. The method according to any one of claims 3-5, characterized in that, The method further includes: The laser head projects a second laser beam onto the target recording layer of the optical disc and detects a second reflected light signal; the second reflected light signal is the light signal of the second laser beam reflected by the target recording layer. A second tracking error TE signal is generated based on the second reflected light signal; The laser head projects a third laser beam onto the tilt detection layer of the optical disc and detects a third reflected light signal; the third reflected light signal is the light signal of the third laser beam reflected by the tilt detection layer. A third tracking error TE signal is generated based on the third reflected light signal; Based on the second TE signal and the third TE signal, the tilt angle between the laser head and the optical disc is adjusted from the second angle to the third angle so that the time-domain waveforms of the second TE signal and the third TE signal are synchronized; the third angle is smaller than the second angle.

7. The method as described in claim 6, characterized in that, The step of adjusting the tilt angle between the laser head and the optical disc from the second angle to the third angle based on the second TE signal and the third TE signal includes: Obtain the time-domain waveforms of the second TE signal and the third TE signal; Adjust the position of the objective lens until the time-domain waveforms of the second TE signal and the third TE signal are synchronized, then stop adjusting the position of the objective lens; wherein, when the adjustment of the objective lens is stopped, the tilt angle between the laser head and the optical disc is the third angle.

8. The method as described in claim 6 or 7, characterized in that, The first angle is no greater than 0.45 degrees, the second angle is no greater than 0.05 degrees, and the third angle is no greater than 0.02 degrees.

9. The method according to any one of claims 1-8, characterized in that, The optical disc includes an independent boot layer and multiple recording layers, with the independent boot layer located below the multiple recording layers, and the tilt detection layer being the independent boot layer.

10. A control device, characterized in that, Includes units or modules for performing the method as described in any one of claims 1-9.

11. A control device, characterized in that, Including control circuits and power supply systems; The power supply system is used to supply power to the control circuit; the control circuit is used to execute the control method as described in any one of claims 1-9.

12. A control system, characterized in that, It includes a control device and a laser head, the control device being used to perform the control method as described in any one of claims 1-9; the laser head being used to emit a laser beam.

13. An optical storage system, characterized in that, It includes the control system as described in claim 12 and the optical disc; the optical disc is used to store data.

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