Optical disc device

Abstract

An optical disc apparatus according to the present invention measures, by an amplitude measurer, a signal amplitude of a portion corresponding to a recording pulse pattern corresponding to a preset multi-valued recording corresponding to 0 to N-1 in a read recording signal; according to the signal amplitude, the light emitting power controller is used for adjusting the power of the laser irradiated on the track, so that the signal amplitude is equal to the set signal amplitude; the optical disc device is capable of stably reading data recorded on a high linear density optical disc by changing a continuous mode in which small recording marks and large recording marks are recorded, respectively, and determining the light emission power required for stable recording of the small recording marks and the light emission power required for stable recording of the large recording marks according to the signal amplitudes obtained thereby. And data on the high-density optical disc can be stably read.

Description

Technical Field

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

[0002] Currently, various optical discs exist as information recording media for storing images, data, and more, including DVDs and Blu-ray discs (registered trademark). From the perspective of space efficiency when storing data, technologies to increase recording capacity per unit volume without increasing disc costs include increasing track density and linear density.

[0003] As a technology for improving line density, Partial Response Most Likelihood (hereinafter referred to as PRML) signal processing technology is widely used. During the recording process on the optical disc track, marks and spaces are used to represent binary signals. When reading the binary signal, the detected read signal is limited to a low frequency based on the frequency characteristics detected in the light beam. This occurs due to the diffraction limit size of the light beam reading out multiple marks and spaces at the same time, which is called inter-symbol interference. PRML signal processing technology is a maximum likelihood decoding technology that estimates the recorded binary signal by comparing and selecting an ideal waveform and a read signal waveform, and the ideal waveform assumes inter-symbol interference. With the increase in line density, PRML signal processing technology that extends the inter-symbol interference width has been used. In addition, the binary signal represented by the mark and space is recorded by emitting a light beam strongly with a time width corresponding to the length of the mark, thereby recording an appropriate mark. Based on the PRML signal processing technology, adjustments are made to the luminous time width and delay position corresponding to the mark to achieve good reading.

[0004] Another technique for increasing linear density is a multi-value recording method that virtually arranges cells at regular intervals in the track extension direction (linear direction) and records three or more marks of different sizes for each cell. This increases linear density by expanding from binary signals to multi-value code signals with three or more values. The aforementioned PRML signal processing technology can also be used to read the original multi-value code signal from a multi-value recorded track.

[0005] In conventional PRML signal processing technology for recording binary signals, it is necessary to appropriately control the start and end positions of marks to reduce the error rate of the read data. Compared to the start and end positions, the state of the mark's midpoint has less influence on the error rate. However, in the PRML signal processing technology for multi-valued recording described in Patent Documents 1 and 2, all waveform shapes of the read signal have roughly the same impact on the data error rate.

[0006] The laser diode used in optical disc devices emits a laser with a wavelength of 405 nm, and the objective lens has a numerical aperture of 0.85. The laser beam is focused onto the optical disc track and scanned to achieve tracking and focus control. Under these wavelength and numerical aperture conditions, the width of the optical disc track must be maintained at approximately 160 nm or greater for stable tracking and focus control. Furthermore, to increase the linear density of recording, the length of the multi-valued recording unit is shorter than the track width, to approximately 100 nm or less.

[0007] For example, in a five-value record ranging from 0 to 4, 0 represents the smallest recorded mark and 4 represents the largest. To ensure stable reading in a variety of noisy environments, it's best to keep the size range of the smallest and largest recorded marks as wide as possible. A sufficiently wide size range makes it easier to decode the five-valued recorded symbol from the read signal. Conversely, if the size range is too small, identifying the five-valued recorded symbol from the read signal becomes difficult.

[0008] In a track, a small recording mark equivalent to a 0 can fit within a single cell length, but a large recording mark equivalent to a 4 cannot, affecting the recording of preceding and following cells. Furthermore, laser light irradiating the track causes heat to accumulate on the recording film on the track surface, gradually increasing the temperature and causing thermal interference between consecutive cells. Therefore, in a five-value recording code, such as a pattern like 44044, the middle 0 is affected by the heat generated by the large recording marks of the preceding and following 4s, making it difficult to accurately record the small recording mark.

[0009] On the one hand, in a mode that continuously records short recording marks such as 00000 and 00100, it is necessary to gradually and accurately record these small recording marks at a low light power. However, during the recording process, the laser irradiation point may deform due to factors such as variations in the thickness of the recording film on the disc track surface and disc warping. In addition, focus control errors during laser scanning on the track can also affect the laser's focus state, causing the laser's focus on the track to deteriorate. This situation is similar to a reduction in light power, making it more difficult to accurately record small recording marks at low light power.

[0010] In maximum likelihood decoding technology involving PRML signal processing technology, the bit error rate generally increases as the noise amplitude increases and the waveform of the read signal is distorted. To achieve the ideal effect of maximum likelihood decoding technology, the noise characteristics need to be white noise and the waveform of the read signal must not be distorted. In multi-value recording, in particular, the waveform shape of all read signals is equally important. As mentioned earlier, when the luminous power deviates from the optimal conditions, the waveform of the read signal is easily distorted, which becomes a problem. If appropriate recording conditions such as luminous power cannot be continuously ensured, the effect of PRML signal processing technology cannot be achieved ideally, resulting in an increase in the bit error rate. In this case, in order to reduce the bit error rate, it is necessary to extend the length of the unit line direction or reduce the number of levels of multi-value recording, thereby reducing the line density conditions. Summary of the Invention

[0011] The present invention discloses an optical disc device to overcome the above technical problems.

[0012] In order to achieve the above object, the technical solution of the present invention is:

[0013] An optical disc device includes: a recording pulse signal generator, a light emitting power controller, a recorder, a reader, and an amplitude measuring device;

[0014] The recording pulse signal generator is used to generate a recording pulse signal capable of controlling the laser emission to be in a continuous pulse shape;

[0015] The light emitting power controller is used to control the power of the laser irradiated onto the track according to the waveform of the recording pulse signal;

[0016] The recorder is used to irradiate the track with laser light to form a recording mark;

[0017] The reader is used to read the signal of the recording mark by detecting the reflected light of the laser irradiated on the track;

[0018] The amplitude measuring device is used to measure the signal amplitude of the portion of the read recording signal corresponding to the preset recording pulse shape pattern; and according to the signal amplitude, the light power controller is used to adjust the laser power irradiated onto the track so that the signal amplitude is equal to the set signal amplitude;

[0019] Among them, the preset recording pulse shape mode is a recording pulse mode corresponding to multi-value recording corresponding to 0 to N-1; N is an integer, N≥3, wherein the recording mark gradually increases from 0 value to N-1 value.

[0020] Beneficial Effects: An optical disc device of the present invention uses an amplitude measuring device to measure the signal amplitude of a portion of a read recording signal corresponding to a preset recording pulse pattern corresponding to a multi-value recording corresponding to 0 to N-1; and uses a light emitting power controller to adjust the laser power irradiated onto the track based on the signal amplitude so that the signal amplitude equals the set signal amplitude. The present invention can stably read data recorded on high-density optical discs. Data on high-density optical discs can be stably read. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 is a schematic structural diagram of an optical disc device according to the present invention;

[0023] Figure 2 is a diagram showing the relationship between the recording symbol signal, the recording pulse signal, and the recording mark in an embodiment of the present invention;

[0024] Figure 3 is a diagram showing the relationship between the recording mark, the equalization signal, and the decoded signal in an embodiment of the present invention;

[0025] FIG4 is a diagram showing expected waveforms of PRML signal processing in an embodiment of the present invention;

[0026] Figure 5 Schematic diagram of continuous recording of recording pulses under low light power and narrow light width in an embodiment of the present invention;

[0027] Figure 6 is a diagram showing the relationship between the amplitude values of recording and reading signals under low light power and narrow light width in an embodiment of the present invention;

[0028] Figure 7 1 is a diagram showing the relationship between the recording pulse signal, the recording mark and the read signal amplitude in the 00100 mode in an embodiment of the present invention;

[0029] Figure 8 Graph showing the relationship between the optical power of a recording pulse signal and the amplitude difference of a read signal in a mode corresponding to 00100 in an embodiment of the present invention;

[0030] Figure 9 Schematic diagram of continuous recording of recording pulses under high luminous power and wide light width in an embodiment of the present invention;

[0031] Figure 10 Schematic diagram of read signals of tracks adjacent to a track after continuous recording under high luminous power and wide light width in an embodiment of the present invention;

[0032] Figure 11 is a relationship diagram of recording and reading signal amplitude values under high luminous power and wide light width in an embodiment of the present invention;

[0033] Figure 12 Graph showing the relationship between the recording pulse signal, the recording mark, and the read signal amplitude corresponding to the 44044 mode in an embodiment of the present invention;

[0034] Figure 13 4 is a relationship diagram between the recording pulse signal optical power and the reading signal amplitude difference corresponding to the 44044 mode in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] This embodiment introduces an optical disc device, such as Figure 1 As shown, in particular, it relates to an optical disc device for recording and reproducing information using multi-value recording from 0 to N-1 (N is an integer greater than or equal to 3) in a track on an optical disc, comprising: a recording pulse signal generator, a light emitting power controller, a recorder, a reader, and an amplitude measuring device;

[0037] The recording pulse signal generator is used to generate a recording pulse signal capable of controlling the laser emission to be in a continuous pulse shape; the recording pulse signal is used to modulate the laser irradiated on the track into a continuous pulse shape to obtain a pulse waveform of the recording pulse signal;

[0038] Specifically, in the recording pulse signal, the laser light emission power corresponds to at least two pulse shape heights, i.e., the laser light emission power includes a first light emission power and a second light emission power. The first light emission power is primarily used for small recording marks associated with 0 in N-value multi-value recording, while the second light emission power is primarily used for large recording marks associated with N-1 in N-value multi-value recording.

[0039] The light emitting power controller is used to control the power of the laser irradiated onto the track according to the waveform of the recording pulse signal;

[0040] Preferably, the power of the laser irradiated onto the track is controlled according to the waveform of the recording pulse signal, including a first luminous power and a second luminous power; the first luminous power is used for the recording mark associated with the 0 value in the N-value multi-value recording; the second luminous power is used for the recording mark associated with N-1 in the N-value multi-straight recording.

[0041] The recorder is used to irradiate the track with laser light to form a recording mark;

[0042] The reader is used to read the signal of the recording mark by detecting the reflected light of the laser irradiated on the track;

[0043] Specifically, the optical head of this embodiment irradiates the modulated laser onto the track to form a recording mark through a laser diode driver and a laser diode; and reads the recording mark signal from the reflected light of the track and obtains the regenerated signal through an objective lens and a photodetector for detecting the reflected light from the optical disc track.

[0044] The amplitude measuring device is used to measure the signal amplitude of the portion of the read recording signal corresponding to the preset recording pulse shape pattern; and to adjust the laser power irradiated onto the track according to the signal amplitude so that the signal amplitude is equal to the set signal amplitude;

[0045] Among them, the preset recording pulse shape mode is a recording pulse mode corresponding to multi-value recording corresponding to 0 to N-1; N is an integer, N≥3, wherein the recording mark gradually increases from 0 value to N-1 value.

[0046] Preferably, the preset recording pulse shape pattern includes: a first pulse shape pattern corresponding to (0, 0, 0, 0, 0) in the N-value multi-value record, and a second pulse shape pattern corresponding to (N-1, N-1, N-1, N-1, N-1) in the multi-value record;

[0047] The amplitude measuring device obtains the first amplitude value of the part corresponding to the preset first recording pulse shape pattern by measuring the read recording signal, so as to adjust the first luminous power according to the first amplitude value; specifically, the first luminous power is adjusted by controlling the first luminous power so that the first amplitude value reaches the set first amplitude reference value.

[0048] The amplitude measuring device obtains the second amplitude value of the part corresponding to the preset second recording pulse shape pattern by measuring the read recording signal, so as to adjust the second luminous power according to the second amplitude value; specifically, the second luminous power is adjusted by controlling the second luminous power so that the second amplitude value reaches the set second amplitude reference value.

[0049] Specifically, the preset recording pulse shape pattern includes a first pulse shape pattern corresponding to (0, 0, 0, 0, 0) in the N-value multi-value record and using a first luminous power, and a second pulse shape pattern corresponding to (N-1, N-1, N-1, N-1, N-1) and using a second luminous power. The luminous power controller adjusts the first luminous power / second luminous power by controlling the first luminous power / second luminous power so that the first amplitude value / second amplitude value reaches a set first amplitude reference value / second amplitude reference value.

[0050] Preferably, the preset recording pulse shape pattern further includes: a third pulse shape pattern corresponding to (0, 0, 1, 0, 0);

[0051] The amplitude measuring device measures the read recording signal to obtain a third amplitude value of a portion corresponding to a preset third recording pulse shape mode, so as to adjust the first light emitting power according to the third amplitude value.

[0052] Specifically, for the third pulse shape mode, the third signal amplitude is measured. The luminous power control circuit controls the first luminous power so that the third amplitude reaches a set third amplitude reference value.

[0053] Preferably, when the difference between the first amplitude value and the third amplitude value reaches a preset first amplitude difference value, the first luminous power value is used as the lower limit luminous power, and the reference power of the first luminous power is determined, and the formula used is as follows:

[0054] Px=(1+α)×P1

[0055] Wherein: Px represents the reference power of the first luminous power; P1 represents the lower limit luminous power; α represents the adjustment coefficient of the reference power of the first luminous power.

[0056] Specifically, in this embodiment, when the difference between the first amplitude value and the third amplitude value reaches a preset first amplitude difference, the first luminous power value at this time is used as the lower limit luminous power, and in order to ensure that the first luminous power is not lower than the lower limit luminous power, the luminous power that is increased by a predetermined proportion relative to the lower limit luminous power is used as the reference power of the first luminous power.

[0057] Preferably, the preset recording pulse shape pattern includes: a fourth pulse pattern corresponding to (N-1, N-1, 0, N-1, N-1);

[0058] The amplitude measuring device measures the read recording signal using the second light emitting power at the position of the N-1 value and the first light emitting power at the position of the 0 value to obtain a fourth amplitude value of a portion corresponding to a preset fourth recording pulse shape pattern;

[0059] When the difference between the second amplitude value and the fourth amplitude value reaches the preset second amplitude difference value, the second luminous power value at this time is used as the upper limit luminous power, and the reference power of the second luminous power is determined. The formula used is as follows:

[0060] Py=(1-β)×P2

[0061] Wherein: Py represents the reference power of the second luminous power; P2 represents the upper limit luminous power; β represents the adjustment coefficient of the reference power of the second luminous power.

[0062] Specifically, in this embodiment, when the difference between the second amplitude value and the fourth amplitude value reaches a preset second amplitude difference value, the luminous power controller uses the second luminous power value at that time as the upper limit luminous power. To ensure that the second luminous power does not exceed the upper limit luminous power, a luminous power that is a certain percentage lower than the upper limit luminous power is set as the reference power for the second luminous power.

[0063] Specifically, for a fourth pulse pattern corresponding to (N-1, N-1, 0, N-1, N-1), the amplitude measuring device measures a pulse shape pattern corresponding to (N-1, N-1, 0, N-1, N-1) in the N-value multi-value record, uses a first luminous power at the 0-value position, and uses a second luminous power at the N-1-value position, and measures a fourth amplitude value corresponding to the fourth pulse pattern. The luminous power control circuit is capable of controlling the second luminous power so that the second amplitude value and the fourth amplitude value reach a predetermined amplitude reference value.

[0064] Specifically, the optical disc device in this embodiment is a device that uses multi-value recording technology to store and read information on the optical disc track. Specifically, this device is capable of performing multi-value recording from 0 to N-1 (N is an integer greater than or equal to 3) on the track. It includes a recording pulse signal generator for generating a recording pulse signal that can control the laser emission to be a continuous pulse shape; a light emitting power controller for controlling the power of the laser irradiated onto the track according to the waveform of the recording pulse signal; a recorder for irradiating the track with the laser irradiated onto the track to form a recording mark; a reader for reading the signal of the recording mark by detecting the reflected light of the laser irradiated onto the track; and an amplitude meter for measuring the signal amplitude of the part of the read recording signal corresponding to the preset recording pulse shape pattern; and using the light emitting power controller to adjust the laser power irradiated onto the track according to the signal amplitude so that the signal amplitude is equal to the set signal amplitude;

[0065] Preferably, the track of the optical disc in this embodiment is composed of a spiral groove, and data is recorded on the raised portion and both sides of the groove. When a recording mark is located in a high point region / low point region of the optical disc track, a fifth amplitude value of the recording mark spreading from the high point region / low point region to an adjacent low point region / high point region is obtained by using the second recording pulse shape pattern. Simultaneously, a sixth amplitude value of a low point region / high point region adjacent to the high point region / low point region where no recording mark is present is obtained.

[0066] When the difference between the fifth amplitude value and the sixth amplitude value reaches the set third amplitude difference, the second light emitting power at this time is used as the upper limit light emitting power, and the reference value of the second light emitting power is determined.

[0067] Specifically, the recorder records a mark on a raised portion (or groove) of the groove, and when the record mark has been recorded on the raised portion (or groove) and a record mark is generated, the amplitude measuring device measures a fifth amplitude measurement value of the record mark spreading from the raised portion (or groove) to an adjacent groove (or raised portion) using the second pulse shape mode, and obtains a sixth amplitude measurement value by detecting in a groove (or raised portion) without a record mark adjacent to the raised portion (or groove) without a record mark.

[0068] When the difference between the fifth amplitude value and the sixth amplitude value reaches the set third amplitude difference, the luminous power value at this time is set as the upper limit luminous power, and the luminous power after the upper limit luminous power is reduced by a predetermined proportion is used as the reference value of the second luminous power to ensure that the second luminous power does not exceed the upper limit luminous power.

[0069] Specifically, Figure 1 FIG. 1 is a structural diagram of the optical disc device 10 in the first embodiment. Figure 1As shown, the optical disc device 10 includes an optical head 101, a spindle motor 102, a servo controller 103, a recording pulse signal generator 104, a modulation circuit 105, an error correction coding circuit 106, a read signal decoding circuit 107, a decoding circuit 108, an error correction decoding circuit 109, a light power controller 110, an amplitude measurement device 111, an interface circuit 112, a buffer memory 113, a system controller 114, and a read-only memory (ROM) 115. The optical disc device 10 does not perform conventional binary recording on the optical disc 100, but rather performs multi-value recording with three or more values.

[0070] The optical disc device 10 is used to record and read user data (a type of recorded data) on an optical disc 100. The optical disc 100 has spiral tracks formed from the inner circumference to the outer circumference. The tracks include groove bottom tracks and groove top tracks between adjacent groove bottom tracks. Both the groove bottom tracks and the groove top tracks can record user data.

[0071] The spindle motor 102 is used to rotate the optical disc 100. The optical head 101 records and reads user data on the optical disc 100 by irradiating the optical disc 100 with laser light.

[0072] The servo controller 103 controls the optical head 101 and the spindle motor 102, focusing the laser light emitted by the optical head 101 onto a track on the optical disc 100 for scanning and controlling access to the target track through movement. The servo controller 103 controls the position of the optical head 101 and the rotation speed of the spindle motor 102, enabling the optical head 101 to scan the optical disc 100 at a predetermined linear velocity.

[0073] The I / F circuit 112 receives user data to be recorded on the optical disc 100 from the host 116 and stores it in the buffer memory 113. The I / F circuit 112 also transmits user data read from the optical disc 100 and stored in the buffer memory 113 to the host 116. At the same time, it also transmits user data stored in the buffer memory 113 to other internal modules, or stores user data received from other internal modules in the buffer memory 113.

[0074] The error correction coding circuit 106 adds a check code for error correction to the user data received from the interface circuit 112 to generate coded data.

[0075] The modulation circuit 105 receives the coded data from the error correction coding circuit 106 and generates a modulated recording signal according to a preset multi-value modulation code.

[0076] The recording pulse signal generator 104 generates a recording pulse signal based on the recording code signal generated by the modulation circuit 105, and drives the laser diode of the optical head 101. A recording mark is formed on the optical disc 100 by heat generated by laser irradiation.

[0077] The light emitting power controller 110 adjusts the light emitting power of the laser diode according to the recording pulse signal, and adjusts it to an appropriate light emitting power to achieve stable recording mark formation.

[0078] Meanwhile, user data recorded on optical disc 100 is read by a read signal decoding circuit 107, a demodulation circuit 108, and an error correction decoding circuit 109. The optical head 101 comprises a laser diode with an emission wavelength of λ, an objective lens with a numerical aperture of N, and a photodetector for detecting reflected light. The optical head 101 irradiates laser light onto the optical disc 100 and detects the light reflected from the optical disc 100. Based on the detected reflected light, the optical head 101 outputs a read signal.

[0079] The read signal decoding circuit 107 recovers the recorded code signal from the read signal and outputs it. Specifically, it compares the read signal with multiple ideal waveforms, selects the closest ideal waveform, and outputs the corresponding recorded code signal, performing PRML signal processing (a type of maximum likelihood method). The characteristics of the ideal waveform take into account the bandwidth limitations caused by the frequency characteristics of laser detection.

[0080] The demodulation circuit 108 demodulates the encoded data from the decoded signal according to a predetermined multi-value modulation code.

[0081] The error correction decoding circuit 109 performs error correction on the demodulated coded data and restores the user data.

[0082] The amplitude measuring device 111 measures the signal amplitude of the portion of the recorded signal read that corresponds to the preset recorded pulse shape pattern. Based on the signal amplitude, the light emitting power controller is used to adjust the laser power irradiated onto the track so that the signal amplitude is equal to the set signal amplitude. The amplitude value can be used to confirm whether the recorded mark meets the requirements.

[0083] The ROM 115 is composed of a flash memory and stores a program used by the system controller 114 to control the entire optical disc device 10 .

[0084] The system controller 114 controls various circuits and communicates with the host computer 116 by executing the program stored in the ROM 115. Figure 1 The control arrows from the system controller 114 to the various components are omitted. In this embodiment, the system controller 114 of the optical disc device 10 is responsible for controlling the operation of various circuits related to recording and reading user data.

[0085] The working principle of the optical disc device 10 in this embodiment is as follows:

[0086] First, the operation process of the optical disc device 10 in this embodiment for recording tracks in the data area of the optical disc 100 will be described.

[0087] The I / F circuit 112 acquires user data and a logical address of a recording destination sent from the host computer 116. The user data is divided into data blocks of a prescribed unit, and each data block is sent to the error correction coding circuit 106.

[0088] The error correction coding circuit 106 adds a check code for correcting errors during reading to the user data of each data block, thereby generating coded data.

[0089] The modulation circuit 105 modulates the coded data to which the check code is added into a recording signal according to a predetermined multi-value modulation code.

[0090] The recording pulse signal generator 104 generates a recording pulse signal based on the recording code signal generated by the modulation circuit 105 to drive the laser diode in the optical head 101. The heat generated by the laser irradiation continuously forms recording marks corresponding to the recording pulse signal on the track of the optical disc 100.

[0091] Figure 2 The figure shows the relationship between the recording symbol signal, the recording pulse, and the recording mark formed on the track. Modulation circuit 105 uses a five-value modulation symbol to generate recording symbol signal 201 consisting of the five values 0 / 1 / 2 / 3 / 4. Recording pulse generation circuit 104 generates recording pulse 202 based on recording symbol signal 201. Laser emission is controlled based on recording pulse 202, and the heat from the laser forms recording mark 204 on track 203.

[0092] Specifically, the laser diode emitted by optical head 101 has a wavelength of 405 nm and a numerical aperture (N) of 0.85. Servo controller 103 receives the light signal reflected from track 203 via the optical head 101's photodetector and performs focusing and tracking control on the laser. Under these wavelength and numerical aperture conditions, the width of optical disc track 203 is set to approximately 160 nm or greater for stable tracking and focusing control. Furthermore, to increase the linear density of recording, the length of each cell is shorter than the width of track 203, approximately 100 nm or less.

[0093] Specifically, in this embodiment, recording marks of different sizes are selected according to the difference in the five-value recording coding signal. When the recording mark is 0, a small recording mark is used; when the recording mark is 4, a large recording mark is used. In order to read stably even in the presence of noise, it is best to ensure the size range of small recording marks and large recording marks as much as possible. If the size range is larger, it will be easier to decode the five-value recording coding signal; but if the size range is smaller, it will become difficult to distinguish the five values from the read signal. For track 203, the recording mark of 0 can be placed in a frame of the length of one unit, but the recording mark of 4 cannot be placed in a frame of the length of one unit and will interfere with the previous and next unit records. In addition, the laser heat on track 203 will accumulate on the recording film, causing the temperature to gradually rise and generating thermal interference between consecutive units.

[0094] Specifically, since the formation of the recording mark 204 will exceed one unit and interfere with the previous and next units, this interference needs to be taken into account when controlling the shape of the recording pulse signal emitted by the laser. The shape of the recording pulse signal 202 is not determined one-to-one according to the single unit value of the recording coding signal 201, but is determined according to the combination pattern of 3 or 5 unit values including the previous and next units. If 5-value modulation coding is adopted and combined with 5 unit interval values, 3125 shapes of the recording pulse signal 202 will be determined. The recording pulse signal 202 of the laser emission waveform, whose laser emission power ( Figure 2 The height of the recording pulse signal 202 in the image) and the emission width ( Figure 2 The pulse time width of the recording pulse signal 202 in the recording pulse signal 202 is variably controlled. Increasing the emission power and extending the emission width can form larger recording marks; decreasing the emission power and shortening the emission width will form smaller recording marks.

[0095] The system controller 114 is responsible for controlling the recording operation. By controlling the servo controller 103, the system controller 114 moves the optical head 101 to a designated position on the optical disc 100. Before reaching the target position, the error correction coding circuit 106 is activated. Once the target position is reached, the modulation circuit 105 and the recording pulse generation circuit 104 begin recording.

[0096] Next, the playback operation of the optical disc device 10 in this embodiment will be described.

[0097] The read signal decoding circuit 107 decodes the read signal output by the optical head 101 through PRML signal processing to generate a decoded signal. The demodulation circuit 108 performs five-value modulation and demodulation on the decoded signal. The error correction decoding circuit 109 performs error correction on the demodulated encoded data and restores the user data.

[0098] Specifically, Figure 3The figure shows the relationship between the recording marks formed on the track, the equalized signal processed by the read signal decoding circuit 107 after the read signal detected by the optical head 101, and the decoded signal decoded from the equalized signal. Since the laser wavelength λ of the optical head 101 is 405 nm and the numerical aperture N of the objective lens is 0.85, the frequency characteristics of the read signal detected from the recording marks 302 continuously formed on the track 301 are roughly fixed. In PRML signal processing, a unit impulse response waveform is defined as the waveform obtained from a single recording mark.

[0099] The read signal decoding circuit 107 is composed of a waveform equalization circuit and a maximum likelihood decoding circuit. The waveform equalization circuit compensates the frequency characteristics of the read signal to make it close to the frequency characteristics of the defined impulse response and outputs an equalized signal 303. The maximum likelihood decoding circuit selects the one closest to the equalized signal 303 from multiple ideal waveforms calculated based on the defined impulse response and the recorded coding signal pattern, decodes it, and outputs a decoded signal 304. Figure 3 In the example, the impulse response is defined as three units (1, 2, 1). By combining the five-value modulation code and the (1, 2, 1) impulse response, the equalized signal 303 and the ideal waveform become a signal waveform with 17 amplitude levels, as shown in the equalized signal 303. Due to warping and eccentricity of the optical disc 100, residual errors in the laser scanning control of the track 301 by the servo controller 103, shape errors of the recording marks on the track 301, etc., the amplitude and frequency characteristics of the read signal will change successively. In the waveform equalization circuit, it is necessary to adaptively correct these changes to approach the defined ideal waveform. Therefore, the waveform equalization circuit includes an adaptive equalization circuit comprising an FIR filter (for correcting the signal waveform) and a coefficient control circuit (for successively controlling the FIR filter coefficients). By properly controlling the waveform equalization circuit, the error rate of the maximum likelihood decoding circuit can be reduced, thereby stably reading user data within the range that can be fully corrected by the error correction decoding circuit 109.

[0100] The system controller 114 is responsible for controlling the aforementioned read operation. Through the servo controller 103, the system controller 114 moves the optical head 101 to the target position. When the optical head reaches the target position, it activates the read signal decoding circuit 107 and demodulation circuit 108, followed by the error correction decoding circuit 109 to recover the user data. The recovered user data is stored in the buffer 113 and then transmitted to the host computer 116 via the interface circuit 112, completing the read operation.

[0101] Amplitude measurement device 111 is used to measure the amplitude of various components of the signal obtained during reading. For example, the 00000 pattern consists of five consecutive zeros; the 00100 pattern consists of only one 1 among a series of zeros; the 44444 pattern consists of five consecutive 4s; and the 44044 pattern consists of only one 0 among a series of 4s. As mentioned above, larger recording marks are preferred, so the amplitudes of the 00000 pattern and the 44444 pattern should be comparable. To confirm that small recording marks are accurately recorded, the amplitude of the 00100 pattern is observed. To confirm that thermal interference from large recording marks is adequately controlled, the amplitude of the 44044 pattern is also observed.

[0102] Based on this measurement result, the system controller 114 adjusts the light emission power control circuit 110 and the recording pulse generation circuit 104. Figure 2 The parameters of the luminous power and luminous width of the recording pulse signal 202 are shown. While ideally, recording marks should be formed under stable conditions, factors such as warping of the optical disc 100, variations in the thickness of the recording film on the track surface, and temperature fluctuations around the optical disc device 10 can affect recording conditions. To stably read user data, it is also necessary to ensure a stable recording state. Amplitude measurement circuit 111 performs measurements, and the system controller 114, luminous power control circuit 110, and recording pulse generation circuit 104 adjust the parameters of the recording pulse signal 202 and luminous power to achieve control of a stable recording state.

[0103] In traditional binary signal recording, when using PRML signal processing for data reading, accurately controlling the start and end positions of recorded marks is crucial to minimizing the bit error rate. In contrast, the state of the middle of a recorded mark has little impact on the bit error rate. However, with PRML signal processing for multi-valued recording, the impact of each part of the read signal waveform on the bit error rate is essentially the same.

[0104] like Figure 2 and Figure 3 As shown, information is recorded by recording marks on optical disc 100, utilizing changes in reflectivity. The reflectivity of the track is higher in areas without marks, while the reflectivity is lower in areas with marks. In areas with lower reflectivity, the amount of light reflected back from the track is reduced. The photodetector in optical head 101 detects the reflected light and converts it into a read signal corresponding to the amount of light.

[0105] During this optical recording and reading process, the noise factors in the read signal include: laser noise caused by laser power fluctuations, optical disc noise caused by factors such as rough track surface, recording noise caused by poor recording mark status, and circuit noise generated by the circuit after the reflected light is detected at the optical head 101 and converted into a read signal.

[0106] In the read signal decoding circuit 107, under normal circumstances, the bit error rate will deteriorate as the noise amplitude increases. The effect of PRML signal processing is most ideal when the noise characteristics are white noise and the read signal waveform is not distorted. Even if the noise characteristics are white, if the read signal amplitude of certain specific modes in the recorded five-value recording code signal is reduced, the effect of PRML signal processing will not be fully exerted, and more errors are likely to occur in these specific modes. In multi-value recording, all shapes of the read signal waveform are equally important. If it is not possible to obtain a roughly uniform read signal amplitude in all multi-value modes, in order to reduce the bit error rate, it is necessary to increase the linear length of the storage unit or reduce the number of multi-value levels of the multi-value recording, thereby reducing the linear density condition.

[0107] Figure 4a and Figure 4b The ideal waveform after the PRML signal processing is performed by the read signal decoding circuit 107 is shown. Figure 3 The equalized signal 303 in FIG is the same as that in FIG. , and the impulse response waveform is defined as (1, 2, 1) over a length of 3 units. Combining the 5-value recording coded signal with the (1, 2, 1) impulse response forms an ideal waveform with 17 amplitude levels. Figure 4a The waveform of 100 unit intervals is displayed. Figure 4b The waveform of 12,000 unit intervals is displayed, which clearly shows that there are 17 amplitude levels. The vertical axis represents the signal amplitude. When the pattern of the recording code sequence in the 3 unit intervals is 000, the signal amplitude is 0, and the recording mark is small; when the pattern is 444, the signal amplitude is 1, and the recording mark is large. Figure 4b As shown, these 17 amplitude levels are equally spaced. While the ideal waveform for PRML signal processing has 125 possible combinations within three unit intervals, during recording, the shape of the recording pulse signal is adjusted using a combination of five unit intervals (3125 possible combinations) to control factors such as thermal interference. Adjusting the shape of the recording pulse signal is often accomplished by adjusting the emission width. However, before adjusting the emission width, it is necessary to first determine the emission power.

[0108] from Figure 2 and Figure 3 As can be seen, a small recording mark of 0 can fit within a frame the length of a single cell, but a large recording mark of 4 cannot, interfering with the recording of adjacent cells. Furthermore, heat from the laser irradiating the track accumulates on the recording film on the track surface, gradually raising its temperature and causing thermal interference between consecutive cells. Therefore, in a five-value recording code pattern like 44044, the central 0 is affected by the heat generated by the large 4 recording marks before and after it, making it difficult to record the small recording mark correctly.

[0109] On the other hand, recording small recording marks like 00000 and 00100 requires recording these small marks one by one at a lower laser power. However, during the recording process, the focus of the laser beam on the track is affected by various factors, including variations in recording sensitivity due to variations in the thickness of the recording film on the disc track surface, deformation of the laser irradiation point due to disc warping, and residual errors in focus control during laser scanning along the track. These effects are equivalent to a reduction in luminous power. Therefore, accurately recording small recording marks one by one at a lower laser power becomes difficult.

[0110] Considering these factors, it is crucial to determine the appropriate light emission power to maintain a stable read signal waveform without distortion. This also determines the size of small and large recording marks.

[0111] like Figure 2 As shown, the luminous power of recording pulse signal 202 (i.e., the height of the recording pulse shape in the figure) uses at least two values (Px and Py). The lower luminous power Px is used to form smaller recording marks, primarily corresponding to zeros in 5-level multi-value recording. The luminous power Py is used to form larger recording marks. First, the Px luminous power required for stable recording of smaller recording marks must be determined, and then the Py luminous power must be determined.

[0112] Figure 5 Demonstrates continuous recording of recording pulses with low luminous power and narrow luminous width. The luminous width is set to a constant T0, and recording is performed by changing the luminous power. Figure 5 Figure 2 shows the process of increasing the luminous power to Pa, Pb, and Pc. The luminous width of the recording pulse generator 104 can be divided into 128 steps per unit time, for example, and a width of 10 to 100 steps can be used. When determining the luminous power Px, a width greater than the minimum width of 10 is used. This is because forming a small recording mark surrounded by thermal interference from a large recording mark, such as the 44044 pattern, requires less laser heat than in the 00000 pattern, and a smaller luminous width must be used.

[0113] To determine the emission power Px, the system controller 114 controls the recording pulse generation circuit 104 to generate a recording pulse signal in a specific pattern to adjust the emission power, rather than generating a recording coding signal through the modulation circuit 105. In addition, it controls the emission power control circuit 110 to gradually change the emission power at a certain interval. This specific pattern for emission power adjustment is a pattern of a continuous emission width T0, and the emission powers Pa, Pb, and Pc gradually increase. After recording the specific pattern for emission power adjustment, the system controller 114 controls the optical disc device 10 to perform a reading operation to obtain the amplitude value of the reading signal from the amplitude measurement circuit 111.

[0114] As Figure 5 shown, on the track 402, a small recording mark is continuously recorded using a recording pulse with an emission power Pa and an emission width T0. When this part is read, the amplitude value of the reading signal is Ma, which is obtained from the amplitude measurement circuit 111. Similarly, when reading the part continuously recorded by the recording pulse with an emission power Pb and an emission width T0, the amplitude value of the reading signal is Mb; when reading the part continuously recorded by the recording pulse with an emission power Pc and an emission width T0, the amplitude value of the reading signal is Mc.

[0115] As described above, due to the influence of various factors, the emission power will decrease, and the effective heat irradiated onto the track will also decrease accordingly. In this case, it is still necessary to record a small recording mark equivalent to the 00000 pattern and obtain the amplitude value of the reading signal. To meet this requirement, the emission power Px can be calculated based on Figure 5 the emission power and the amplitude measurement values shown in

[0116] Figure 6 shows the relationship between the emission power and the amplitude value of the reading signal. Based on the emission power Pa and the amplitude value Ma, the emission power Pb and the amplitude value Mb, and the unrecorded amplitude value M0, the boundary emission power P0 at which the recording mark no longer forms is calculated according to the following formula (1).

[0117] P0 = Pa - (Pb - Pa) * (Ma - M0) / (Mb - Ma) (1)

[0118] where, P0 represents the boundary emission power at which the recording mark no longer forms; Pa and Pb both represent emission powers, where Pa < Pb; M0 represents the unrecorded amplitude value; Mb represents the amplitude value of the reading signal when using the emission power Pb; Ma represents the amplitude value of the reading signal when using the emission power Pa;

[0119] During the operation of the optical disc device 10, the luminous power and the actual heat will drop by about 10%. Therefore, for example, even if the luminous power Pa is reduced by 10% to a value of 0.9×Pa, it is necessary to be able to stably record small recording marks. Figure 6 As shown, the value of 0.9×Pa is lower than P0, so recording is impossible. This does not meet the requirement of being able to record small recording marks even when the luminous power drops by about 10%. To meet this condition, the reference luminous power should be about 10% higher than the boundary luminous power P0 calculated in Formula 1. For example, taking a 15% margin, it can be determined using the following formula (2).

[0120] Px=1.15×P0 (2)

[0121] Figure 7 The relationship between the recording pulse signal, recording mark, and read signal amplitude values in the 00100 pattern is shown. Figure 5 In the example, the luminous width of all recorded pulse signals is fixed to T0, and Figure 7 The luminous power and the recording pulse signal are included. Since the luminous width T1 corresponds to the "1" part in the 00100 pattern, it is wider than the luminous width T0. Figure 5 The system controller 114 is the same as the Figure 7 The recording operation is performed using the recording pulse signal shown, and the amplitude value of the read signal is acquired from the amplitude measurement circuit 111 to control the read operation.

[0122] like Figure 7 As shown, under the continuous application of recording pulses with luminous power Pa and luminous widths T0 and T1, small recording marks are recorded on track 402. The recording mark corresponding to the portion with luminous width T1 is slightly enlarged. When reading this portion, the amplitude values of the read signal are Ma and Ma+Da, and these amplitude values can be obtained from amplitude measurement circuit 111. Similarly, when reading the portion recorded by the continuous application of recording pulses with luminous power Pb, the amplitude values of the read signal are Mb and Mb+Db; when reading the portion recorded by the continuous application of recording pulses with luminous power Pc, the amplitude values of the read signal are Mc and Mc+Dc. From these measured values, the amplitude difference values Da, Db, and Dc corresponding to the increase in the portion 1 in the 00100 pattern can be obtained. Even when the luminous power and actual heat are reduced, it is essential to ensure that the small differences in recording mark size corresponding to the 00100 pattern are recorded and that appropriate read signal amplitude values can be obtained.

[0123] Figure 8The relationship between the luminous power and the read signal amplitude difference value is shown. From the luminous power Pa and the amplitude difference value Da, and the luminous power Pb and the amplitude difference value Db, the boundary luminous power P1 that ensures a small recording mark size difference can be calculated using the following formula (3).

[0124] P1=Pa-(Pb-Pa)·Da / (Db-Da) (3)

[0125] Similarly, for example, when the luminous power Pa is used as a reference, it is necessary to ensure that the difference in the recording mark size can be kept stable even if it drops by 10% to 0.9×Pa. Figure 8 As shown, 0.9×Pa is lower than P1. Therefore, when the luminous power drops by about 10%, it is not possible to maintain the difference in the recording mark size. To meet this condition, the reference luminous power should be higher than the boundary luminous power P1 calculated by formula 3 by about 10%. For example, if a 15% margin is taken, the calculation is performed using formula (4):

[0126] Px=1.15×P1 (4)

[0127] In addition, the amplitude difference Dx estimated at the luminous power Px can also be obtained through a similar calculation method.

[0128] The luminous power Px when recording a small recording mark can be calculated by two methods. The first is to use Figure 5 and Figure 6 The measured value in is calculated using Formula 2; the second is obtained by Figure 7 and Figure 8 The measured values in are calculated using Formula 4. To ensure both conditions are met, the larger value should be selected. If P0 in Formula 1 and P1 in Formula 3 are larger, Px is determined as 1.15 × P0. This method can determine the luminous power Px required to record a smaller mark.

[0129] Next, it is necessary to determine the light emission power Py in the mode for forming a large recording mark.

[0130] Figure 9 This demonstrates the continuous recording of pulses at high luminous power and wide luminous width. The luminous width is fixed at T2, and recording is performed by changing the luminous power. Figure 9Figure 1 shows the case where the luminous power is increased sequentially to Pd, Pe, and Pf. The recording pulse generation circuit 104 divides the time of one unit interval into 128 steps, allowing for widths of 10 to 100. When determining luminous power Py, the luminous width T2 is set to be less than the maximum width of 100. This is because when forming small recording marks such as the 00400 pattern and sandwiching them between larger recording marks at low heat levels, higher laser heat is required than with the 44444 pattern, thus requiring a larger luminous width to be used.

[0131] To determine the luminous power Py, the system controller 114 does not directly send the recording signal generated by the modulation circuit 105 to the recording pulse generation circuit 104. Instead, it controls the recording pulse generation circuit 104 to generate a recording pulse signal with a specific pattern for adjusting the luminous power. Simultaneously, the system controller also controls the luminous power control circuit 110 to gradually adjust the luminous power within a certain range. The specific pattern for adjusting the luminous power includes a continuous portion with a luminous width of T2, and the luminous power increases sequentially from Pd, Pe, and Pf. If recording is performed using only the continuous pattern with a luminous width of T2, the track will maintain a low reflectivity for a long period of time, causing the servo controller 103 to control focus and tracking instability. To achieve stable operation, it is necessary to include not only a continuous portion with a luminous width of T2 but also a continuous portion with a shorter luminous width. After recording the specific pattern for adjusting the luminous power, the system controller 114 controls the optical disc device 10 to perform a read operation to obtain the amplitude value of the read signal from the amplitude measurement circuit 111.

[0132] like Figure 9 As shown, a large recording mark is recorded on track 902, generated by continuous recording pulses with a light power of Pd and a light width of T2. When this portion is read, the amplitude of the read signal is Md, which can be obtained by amplitude measurement circuit 111. Similarly, when a portion is read by continuous recording pulses with a light power of Pe and a light width of T2, the amplitude of the read signal is Me; and when a portion is read by continuous recording pulses with a light power of Pf and a light width of T2, the amplitude of the read signal is Mf.

[0133] Due to various factors, the luminous power may decrease and the effective heat may also decrease, but sometimes the control error of the luminous power control circuit 110 may cause the luminous power to increase. In the case of increased luminous power, it is necessary to ensure that the large recording mark corresponding to the 44444 pattern is not too large. Figure 9As can be seen in the figure, due to the excessively large recording pulse power Pf and width T2, the recording mark in the continuous recording portion is too large, exceeding the track width and being recorded onto the adjacent track. On optical disc 100, the track is formed by spiral grooves, and data can be recorded both in the grooves and between the grooves. If the recording mark is too large, the groove mark will extend into the inter-groove area, affecting data recording and reading in the inter-groove area. Therefore, it is very important to control the large recording mark so that it does not exceed the track width.

[0134] Figure 10 Shown in Figure 9 The amplitude measurement circuit 111 measures the read signal amplitude in track 1004, which is adjacent to track 1002 where a recording mark is recorded. When recording pulses with a light emitting power of Pd and a light emitting width of T2 are continuously recorded near the track, the read signal amplitude is Wd; when recording pulses with a light emitting power of Pe and a light emitting width of T2 are continuously recorded, the amplitude is We; and when recording pulses with a light emitting power of Pf and a light emitting width of T2 are continuously recorded, the amplitude is Wf. Figure 9 The amplitude of the signal read on the recording track gradually approaches saturation from Me to Mf. Figure 10 The amplitude values Wd and We of the read signal on the adjacent track 1004 are close, while Wf is significantly increased. Because the recording pulse with light power Pf generates more heat, the recorded mark becomes wider than the width of track 1002 and extends into the adjacent track 1004. Therefore, the amplitude value Wf increases dramatically compared to Wd and We, which do not extend into the adjacent track 1004.

[0135] Figure 11 The relationship between the luminous power and the amplitude of the read signal is shown. The luminous power P2 at the boundary where the recording mark exceeds the track width can be calculated using the following formula (5) using the luminous power Pd and the amplitude value Md, the luminous power Pe and the amplitude value Me, and the amplitude value Mf where the amplitude gradually approaches saturation:

[0136] P2 = Pe + (Pe - Pd) * (Mf - Me) / (Me - Md) (5)

[0137] When the optical disc device 10 is in operation, the luminous power increases by about 5% to 10%. For example, when the luminous power Pe is used as a reference, even if it increases by 10% to a value of 1.1×Pe, it should not exceed the track width. However, since the value of 1.1×Pe is Figure 11 As shown, the reference luminous power is higher than P2, which will result in a larger recording mark exceeding the track width, which does not meet the requirements. To meet this condition, the reference luminous power should be about 10% lower than the boundary luminous power P2 calculated in formula 5. For example, a 10% margin can be reserved and determined using formula (6).

[0138] Py=0.9×P2 (6)

[0139] Figure 12 The relationship between the recording pulse signal, recording mark and read signal amplitude in 44044 mode is shown. Figure 9 In the example, the luminous width of all recording pulses is set to a fixed T2, but in Figure 12 In the example, there is a recording pulse with a luminous width of T3 at the luminous power Px. This recording pulse with a luminous width of T3 corresponds to the "0" portion in the 44044 pattern. Since it is sandwiched between two recording marks with a value of "4", its luminous power is set to a lower Px and the luminous width T3 is the minimum width. The recording pulse generation circuit 104 divides one unit time into 128 steps, and can use 10 to 100 steps, so the luminous width T3 can be set to 10. The luminous power of the recording pulse with a luminous width of T2 is the same as Figure 9 The system controller 114 controls Figure 12 The recording pulse signal shown performs a recording operation and controls a reading operation to acquire the amplitude value of the read signal from the amplitude measurement circuit 111 .

[0140] like Figure 12 As shown, under the continuous action of recording pulses with luminous power Pd and luminous widths T2 and T3, small recording marks are recorded on track 1202. When the luminous width is T3, the recorded mark becomes smaller. When reading this part, the amplitude values of the read signal are Md and Md-Dd, and these values can be obtained from the amplitude measurement circuit 111. Similarly, when reading the part recorded under the action of recording pulses with luminous power Pe and Pf, the amplitude values of the read signal are Me and Me-De, and Mf and Mf-Df, respectively. From these measured values, the small amplitude differences Dd, De, and Df corresponding to the 0 part in the 44044 pattern can be obtained. Even when the luminous power is increased, it is necessary to ensure that the size differences of the small recording mark parts in the 44044 pattern are retained and the read signal is obtained as an appropriate amplitude value.

[0141] Figure 13 The relationship between the luminous power and the difference in the read signal amplitude is shown. By the following formula (7), we can calculate the Figure 8 The boundary luminous power P3 required for the amplitude difference greater than the 00100 mode amplitude difference Dx is shown in FIG.

[0142] P3=Pd+(Pe-Pd)*(Dx-Dd) / (De-Dd) (7)

[0143] Figure 12When the luminous power Py is obtained by using the aforementioned formula 5 and formula 6, the estimated value of the amplitude difference Dy can be obtained by a similar calculation method. Figure 8 The amplitude difference Dx of the 00100 pattern ensures that the amplitude difference Dy is much larger than the amplitude difference Dx when the luminous width is minimized. Furthermore, this ensures that the luminous power P2 remains lower than P3 when the luminous power rises by approximately 10%. If the luminous power P3 is lower than P2, use formula (8) instead of formula 6 to determine Py.

[0144] Py=0.9×P3 (8)

[0145] By implementing the above method, the system controller 114 determines the Px light emission power for stably recording a small recording mark and the Py light emission power for recording a large recording mark of an appropriate size.

[0146] In this embodiment, the luminous power is calculated using linear calculations based on the amplitude measurements. However, this is not the only method; a polynomial approximation can also be used. Furthermore, while the examples illustrate a continuous recording pattern of small and large recording marks, this is not limiting; any continuous recording pattern containing both small and large recording marks can achieve the same effect.

[0147] In summary, in this embodiment, the optical disc 100 and optical disc drive 10 optimize the recording light power, minimizing waveform distortion in the read signal. This allows the full effectiveness of PRML signal processing technology for reading signals from multi-valued tracks, preventing an increase in the bit error rate. Without reducing linear density, for example by extending the linear length of the cell direction or reducing the number of multi-valued recording levels, data on the optical disc can still be stably read at high linear densities.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical disc device, characterized in that: include: Recording pulse signal generator, luminous power controller, recorder, reader, amplitude measurer; The recording pulse signal generator is used to generate a recording pulse signal capable of controlling the laser emission to be in a continuous pulse shape; The light emitting power controller is used to control the power of the laser irradiated onto the track according to the waveform of the recording pulse signal; The recorder is used to irradiate the track with laser light to form a recording mark; The reader is used to read the signal of the recording mark by detecting the reflected light of the laser irradiated on the track; The amplitude measuring device is used to measure the signal amplitude of the portion of the read recording signal corresponding to the preset recording pulse shape pattern; Using the light emitting power controller to adjust the laser power irradiated onto the track according to the signal amplitude, so that the signal amplitude is equal to the set signal amplitude; Among them, the preset recording pulse shape mode is a recording pulse mode corresponding to multi-value recording corresponding to 0 to N-1; N is an integer, N≥3, wherein the recording mark gradually increases from 0 value to N-1 value.

2. The optical disc device according to claim 1, wherein: According to the waveform of the recording pulse signal, the power of the laser irradiated onto the track is controlled, including a first light emitting power and a second light emitting power; The first light emitting power is used for a record mark associated with a 0 value in an N-value multi-value record; The second light emission power is used for recording marks associated with N-1 in N-value multi-line recording.

3. The optical disc device according to claim 2, wherein: The preset recording pulse shape pattern includes: a first pulse shape pattern corresponding to (0, 0, 0, 0, 0) in the N-value multi-value record, and a second pulse shape pattern corresponding to (N-1, N-1, N-1, N-1, N-1) in the multi-value record; The amplitude measuring device measures the read recording signal to obtain a first amplitude value of a portion corresponding to a preset first recording pulse shape pattern, so as to adjust the first light emission power according to the first amplitude value; The amplitude measuring device measures the read recording signal to obtain a second amplitude value of a portion corresponding to a preset second recording pulse shape pattern, so as to adjust the second light emitting power according to the second amplitude value.

4. The optical disc device according to claim 3, wherein: The preset recording pulse shape mode includes: a third pulse shape mode corresponding to (0, 0, 1, 0, 0) in the multi-valued recording; The amplitude measuring device measures the read recording signal to obtain a third amplitude value of a portion corresponding to a preset third recording pulse shape mode, so as to adjust the first light emitting power according to the third amplitude value.

5. The optical disc device according to claim 4, wherein: When the difference between the first amplitude value and the third amplitude value reaches the preset first amplitude difference value, the first luminous power value at this time is used as the lower limit luminous power, and the reference power of the first luminous power is determined. The formula used is as follows: Px=(1+α)×P1 Wherein: Px represents the reference power of the first luminous power; P1 represents the lower limit luminous power; α represents the adjustment coefficient of the reference power of the first luminous power.

6. The optical disc device according to claim 3, wherein: The preset recording pulse shape mode includes: a fourth pulse mode corresponding to (N-1, N-1, 0, N-1, N-1) in a multi-valued recording; The amplitude measuring device obtains a fourth amplitude value of a portion corresponding to a preset fourth recording pulse shape pattern by measuring the read recording signal; When the difference between the second amplitude value and the fourth amplitude value reaches the preset second amplitude difference value, the second luminous power value at this time is used as the upper limit luminous power, and the reference power of the second luminous power is determined. The formula used is as follows: Py=(1-β)×P2 Wherein: Py represents the reference power of the second luminous power; P2 represents the upper limit luminous power; β represents the adjustment coefficient of the reference power of the second luminous power.

7. The optical disc device according to claim 3, wherein: The optical disc track is composed of a spiral groove. When a recording mark is located in a high point region / low point region of the optical disc track, a second pulse shape pattern is used to obtain a fifth amplitude value of the recording mark spreading from the high point region / low point region to an adjacent low point region / high point region. Simultaneously, a sixth amplitude value of a low point region / high point region adjacent to the high point region / low point region without a recording mark is obtained. When the difference between the fifth amplitude value and the sixth amplitude value reaches the set third amplitude difference, the second light emitting power at this time is used as the upper limit light emitting power, and the reference value of the second light emitting power is determined.

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