JP4268312B2 - Optical recording / reproducing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical recording / reproducing apparatus capable of recording information according to a mark edge recording method and reproducing information from the recording medium by irradiating an optical recording medium such as an optical disk with laser light. About. In particular, the present invention relates to an optical recording / reproducing apparatus capable of preventing the center of a mark to be formed from becoming thin even when the recording sensitivity of a recording medium is low.
[0002]
[Prior art]
As recording media capable of optically rewriting information, phase change recording media and magneto-optical recording media are known.
[0003]
When information is written on the phase change recording medium, the recording film of the recording medium is irradiated with the focused laser beam to heat and melt the recording film. Since the temperature reached and the cooling process of the recording film differ depending on the laser light intensity level, it is possible to locally change the optical properties (refractive index, etc.) of the recording film by modulating the laser light intensity. is there. More specifically, when the intensity of the laser beam exceeds a predetermined level, the irradiated portion of the recording film is rapidly cooled from a high temperature state and thus becomes amorphous. On the other hand, when the laser beam is relatively weak, the irradiated portion of the recording film is gradually cooled from the middle-high temperature state and thus crystallizes. In the recording film, the amorphous part is called “mark”, and the crystallized part is called “space”. Optical characteristics such as refractive index are different between the mark and the space. It is possible to store binary information by an arrangement of marks and spaces.
[0004]
When reproducing recorded information from a phase change recording medium, the recording film is irradiated with laser light (reproduced light) that is weak enough not to cause a phase change in the recording film, and the reflected light is detected. The amorphous mark portion has a relatively low reflectance, and the crystallized space portion has a relatively high reflectance. Therefore, a reproduction signal can be obtained by detecting a difference in light quantity between the reflected light from the mark and the reflected light from the space.
[0005]
As an information recording method, there are a pulse position modulation method (PPM: Pulse Position Modulation) and a pulse width modulation method (PWM: Pulse Width Modulation). Recording by the pulse width modulation method is also called mark edge recording.
[0006]
In PPM recording, a relatively short mark having a constant pulse width is recorded with various lengths of space, and recording information is assigned to the mark position. On the other hand, in PWM recording, marks of various lengths are recorded with spaces of various lengths, and recording information is assigned to both the mark length and the space length. Usually, the information recording density can be increased by adopting PWM rather than PPM.
[0007]
When performing PWM recording, a long mark is recorded as compared with PPM recording. When a long mark is recorded on the phase change recording medium, the mark width (size perpendicular to the track direction) may become non-uniform due to the heat storage / heat dissipation effect of the recording film and the variety of recording sensitivity. It is also known that if a recording film is continuously irradiated with a recording light to form one long mark, heat is excessively accumulated in the latter half of the long mark and the mark width is widened. For this reason, even when one mark is formed, a system (write strategy) in which the recording light is composed of a plurality of shorter pulses is employed. A method and a recording / reproducing apparatus for forming each mark using a plurality of pulses are disclosed in, for example, US Pat. No. 5,490,126 and US Pat. No. 5,636,194.
[0008]
2A to 2D show the waveform of the recording light, the shape of the mark formed on the recording film, the waveform of the reproduction signal, and the binarized signal formed from the reproduction signal, respectively. Note that the waveform of the recording light is defined by the waveform of the electrical signal used for modulating the recording light. This electric signal is called a recording pulse. The power of the recording light is proportional to the amplitude of the recording pulse. Depending on the nature of the light source of the recording light (for example, a semiconductor laser), there may be a non-essential difference between the waveform of the recording light and the waveform of the recording pulse. In this specification, the waveform of the recording light and the recording The pulse waveform is not strictly distinguished.
[0009]
First, reference is made to FIG. The recording light used to form one mark is composed of a front end pulse 1, a comb pulse train 2, and a rear end pulse 3 arranged in the time axis direction. The power of this recording light is modulated between peak power (Pp), bias power 1 (Pb1), and bias power 2 (Pb2).
[0010]
During the period when the recording medium is irradiated with the recording light and each mark is being formed on the recording film (hereinafter referred to as “mark interval”), the power of the recording light is peak power (Pp) and bias power 2 (Pb2). Is modulated between. On the other hand, during the period in which each space is being formed in the recording film (hereinafter referred to as “space section”), the power of the recording light is maintained at the bias power 1 (Pb1).
[0011]
In general, an optical recording / reproducing apparatus needs to appropriately execute information recording / reproducing with respect to an optical recording medium having various recording characteristics. When recording the information with the average power of the recording light (average value in the mark section) fixed to a certain level, the length and width of the mark formed on the recording medium having a relatively low recording sensitivity tend to decrease. is there. For this reason, in the conventional optical recording / reproducing apparatus, after the initial setting of an appropriate optical power according to the recording sensitivity of the recording medium, the compensation operation of the recording optical power is performed in order to make the length and width of the mark appropriate. Is executed (recording optical power learning). In such an optical recording / reproducing apparatus, a comparatively short mark is recorded on a test basis, and the recording light power is compensated so that the short mark can be recorded accurately. This is because it was the most important issue to appropriately record a short mark with a small reproduction amplitude intensity.
[0012]
[Problems to be solved by the invention]
However, the present inventor has found that even if the conventional recording light power compensation is performed, a reading error inevitably occurs. The present inventor has found that the cause of such a reading error is caused by a relatively long mark, and has come up with the present invention.
[0013]
Hereinafter, the analysis results of the inventor regarding the prior art will be described.
[0014]
First, reference is made to FIG. A mark 4 shown in FIG. 2B is an example of a mark formed when the thermal energy of the comb pulse train 2 (= “average power in the mark section of recording light”) is insufficient. The width of the mark 4 is relatively wide at the front end portion and the rear end portion of the mark, and is narrow in an intermediate region between the front end portion and the rear end portion. Such a mark shape is referred to as “medium thinning”.
[0015]
When such a mark 4 is irradiated with reproduction light, and the reflected light is received by a photodetector and converted into an electrical signal, reproduction having a bimodal waveform as shown in the left part of FIG. Signal 5 is obtained. When the reproduction signal 5 is binarized with the threshold 6 as a reference, as shown in the left part of FIG. 2D, two divided pulses 7 and 8 are generated, and the position of the edge of the mark 4 and the mark The length cannot be detected correctly. If the mark edge and mark length cannot be detected correctly, an error in reading the recorded data occurs.
[0016]
In this specification, the reproduction signal from a part of one mark (the part located between the front edge and the rear edge of the mark) becomes relatively small, and as a result, the reproduction signal is binarized. A portion recognized as “space” instead of “part of the mark” is referred to as “read error inducing portion”.
[0017]
Even in the conventional optical recording / reproducing apparatus, in the recording light power compensation process, when the system controller in the apparatus detects an increase in the reading error, the recording light power is adjusted so as to reduce the reading error. It was. The right part of FIG. 2 shows conventional compensation. According to the conventional recording light power compensation method, each power level of the recording light is increased α times (α> 1), and recording light having a waveform as shown in the right part of FIG. Will be irradiated. Here, the relationship of Pp ′ = α × Pp, Pb1 ′ = α × Pb1, and Pb2 ′ = α × Pb2 is established. When the three power levels are uniformly increased in this way, as shown in the right part of FIG. 2B, the mark 10 having a length and width that is too large compared to the mark 9 having the target shape is formed. Will be. When the mark 10 whose length and width are too large is reproduced, as shown in FIG. 2C, a reproduction signal 12 having a waveform spreading laterally beyond the target reproduction signal 11 is obtained. When the reproduction signal 12 is binarized with the threshold value 6 as a reference, a mark length 14 is detected as a mark length 14 longer than the proper mark length 13 as shown in FIG. The length cannot be detected correctly, and a reading error occurs.
[0018]
Note that the above problem is not unique to the phase change recording medium, and may also occur in other optical recording media such as a magneto-optical recording medium.
[0019]
The present invention has been made in view of the above circumstances, and the object of the present invention is to further improve the conventional recording light power compensation and to appropriately detect whether a relatively long mark is thinned or not. Another object of the present invention is to provide an optical recording / reproducing apparatus capable of correcting the recording light power so as to form a long mark having an appropriate shape.
[0020]
[Means for Solving the Problems]
The optical recording / reproducing apparatus according to the present invention irradiates a recording film of a rewritable recording medium with a pulsed light beam, thereby causing nine types of lengths indicated by 3T to 11T by 8/16 modulation recording encoding method. An optical recording / reproducing apparatus capable of forming a plurality of marks having a thickness on the recording film, recording a test mark having a length of 7T or more on the recording film, and reproducing the test mark, The average value of the power of the light beam with respect to a part of the mark is changed so as to make the width of the mark having a length of 7T or more uniform.
[0021]
An optical recording / reproducing apparatus according to the present invention irradiates a recording film of a recording medium with a pulsed light beam, locally changes the optical characteristics of the recording film, and thereby relates to information to be recorded. An optical recording / reproducing apparatus capable of forming a plurality of marks on the recording film, wherein information for generating recording pulses (write pulses) for forming the marks and modulating the light beam by the recording pulses A writing means, an information reproducing means for detecting a change in optical characteristics of a portion including the mark formed on the recording film, and at least one test mark having a length greater than a selected length. In the long mark data generation circuit to be written on the recording film by the information writing means, and in the test mark, the change in the optical characteristic is for the reproduction of the test mark. And a mark width determination processing circuit for determining whether or not there is a non-minute read error inducing portion, and if it is determined that the read error inducing portion is present in the test mark, at least the length of the test mark When forming a mark having the above length, the average value of the power of the light beam is increased from the initial setting level, thereby correcting the power so that the read error inducing portion does not occur in the mark. To do.
[0022]
In the correction of the power, it is preferable to partially increase the average value of the power of the light beam at the center of the mark to be formed.
[0023]
In a preferred embodiment, the information writing means generates two or more pulses including a front end pulse and a rear end pulse spaced from the front end pulse as a recording pulse for forming each mark, and the mark The length of depends on the number of pulses.
[0024]
The power correction is preferably performed by changing the amplitude of at least one pulse located between the front end pulse and the rear end pulse. The power correction may be performed by changing the duty of at least one pulse positioned between the front end pulse and the rear end pulse.
[0025]
In a preferred embodiment, a memory for storing information defining the power may be provided, and after the correction of the power is completed, the information defining the power after correction may be stored in the memory.
[0026]
It is preferable that after the recording medium is loaded, the power compensation and the widths of the front and rear end pulses are executed, and the power correction is executed after the compensation is completed.
[0027]
A light beam having the corrected power may be used only when a mark having a certain length or more is formed among the plurality of marks associated with information to be recorded.
[0028]
The test mark preferably has a length that is equal to or greater than the average of the maximum and minimum lengths of a plurality of marks to be formed when writing data.
[0029]
In a preferred embodiment, the test mark has a length of 7T or more in an 8/16 modulation scheme.
[0030]
In a preferred embodiment, the test mark has a length of 11T in an 8/16 modulation scheme.
[0031]
In a preferred embodiment, after loading of the recording medium, a test mark having a length of 6T or less in an 8/16 modulation system is formed to compensate for the power and the width of the front and rear end pulses. After the compensation is completed, the power is corrected.
[0032]
In a preferred embodiment, the mark width determination processing circuit determines whether or not the read error inducing portion exists in the test mark based on a mark edge jitter obtained from the reproduction signal of the test mark. .
[0033]
In a preferred embodiment, the mark width determination processing circuit determines whether or not the read error inducing portion exists in the test mark based on a bit error amount obtained by demodulating the reproduction signal of the test mark. Judging.
[0034]
In a preferred embodiment, the mark width determination processing circuit determines whether or not the read error inducing portion exists in the test mark based on a measured value of the mark length obtained by demodulating the reproduction signal of the test mark. Determine whether.
[0035]
The read error inducing portion has a relatively low reproduction signal level, and as a result, the single test mark is erroneously binarized so as to include two or more marks.
[0036]
In a preferred embodiment, the information writing means includes a light beam driving circuit that drives a light source of the light beam, and a recording pulse generation circuit connected to the light beam driving circuit, and the recording pulse generation The circuit generates a recording pulse based on information defining the waveform of the recording pulse and supplies the recording pulse to the light beam driving circuit.
[0037]
In a preferred embodiment, the long mark data generation circuit causes the recording pulse generation circuit to generate a recording pulse for the test mark based on information defining a recording pulse for the test mark.
[0038]
In a preferred embodiment, the optical recording / reproducing apparatus includes a nonvolatile memory in which information defining a waveform of the recording pulse is stored.
[0039]
In a preferred embodiment, the optical recording / reproducing apparatus includes a memory area in which information necessary for defining a corrected recording pulse is stored.
[0040]
In a preferred embodiment, the information reproducing means includes an optical system that irradiates the recording medium with reproduction light, a photodetector that receives the reproduction light reflected from the recording medium and converts it into an electrical signal, and the light. And a circuit for generating binary data based on a signal output from the detector.
[0041]
Another optical recording / reproducing apparatus according to the present invention irradiates a recording film of a rewritable recording medium with a pulsed light beam to locally change the optical characteristics of the recording film, thereby recording. An optical recording / reproducing apparatus capable of forming a plurality of marks associated with information on the recording film, wherein at least one test mark having a length equal to or longer than a selected length is formed on the recording film. A step of writing; a step of detecting a change in optical characteristics of a portion of the recording film including the test mark; and a reading error in which the change in optical characteristics is not sufficient for reproduction of the test mark in the test mark A test recording operation including a step of determining whether or not an inducing portion exists is determined, and it is determined that the read error inducing portion is present in the test mark. If the, when forming a mark having a length longer than at least the test mark, increases the average value of the power of the light beam from the initial setting level.
[0042]
In a preferred embodiment, when it is determined that the read error inducing portion is present in the test mark, the light beam having an average power increased from a certain setting level to the next setting level is used. The test mark is formed on the recording film, and then the step of determining whether or not the read error inducing portion exists in the test mark is performed at least once.
[0043]
In a preferred embodiment, when it is determined that the read error inducing portion exists in the test mark, the light beam is used by increasing an average power value from a certain setting level to a plurality of different setting levels. , N types (N is an integer of 2 or more) of test marks are formed on the recording film, and then a step of determining whether or not the read error inducing portion exists in any of the test marks is performed at least once. Do.
[0044]
In a preferred embodiment, before performing the step of writing the test mark to the recording film, compensation of the power of the light beam is performed for a mark shorter than the test mark.
[0045]
Still another optical recording / reproducing apparatus according to the present invention irradiates a recording film of a rewritable recording medium with a pulsed light beam to change the optical characteristics of the recording film, thereby obtaining information to be recorded. An optical recording / reproducing apparatus capable of forming a plurality of associated marks on the recording film, a memory storing information defining a pulse train for driving a light source of the light beam, and the memory A recording circuit for generating the pulse train based on the stored information, a reproducing circuit for generating reproduction data from a mark formed on the recording film, and a recording / reproducing circuit connected to the recording circuit and the reproducing circuit; A control circuit for controlling the reproduction operation, wherein the control circuit performs a recording / reproduction operation for a mark having a length equal to or longer than a selected length, and sets the length. One is programmed to update said information stored in the memory to optimize the pulse train for the mark.
[0046]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an optical recording / reproducing apparatus according to the present invention will be described with reference to the drawings.
[0047]
[Long mark detection for long marks]
First, reference is made to FIG. FIG. 3A shows the waveform of the recording light used for forming three types of marks having different lengths, that is, the waveform of the recording pulse. Each recording light includes a plurality of pulses, that is, a front end pulse 1, a comb pulse train 2, and a rear end pulse 3.
[0048]
As shown in FIG. 3A, the recording light power is modulated between peak power (Pp), bias power 1 (Pb1), and bias power 2 (Pb2). Here, the relationship Pp>Pb1> Pb2 is established. Pp, Pb1 and Pb2 may be set to, for example, 10 mW (milliwatt), 6 mW, and 2 mW, respectively.
[0049]
In the present embodiment, the recording light intensity is modulated between the peak power (Pp) and the bias power 2 (Pb2) during the period (mark interval) in which each mark is being formed on the recording film. On the other hand, the power of the recording light is maintained at the bias power 1 (Pb1) during the period in which each space is being formed in the recording film (space section).
[0050]
In the write strategy employed in the present embodiment, the pulse widths of the front end pulse 1 and the rear end pulse 3 are set wider than the pulse width of the comb pulse train 2, respectively. Accordingly, the average energy given to the recording film by the comb pulse train 2 is smaller than the average energy given to the recording film by each of the front end pulse 1 and the rear end pulse 3. The pulse widths of the front end pulse 1 and the rear end pulse 3 are typically 1.0T to 1.5T, and each pulse width of the comb pulse train 2 is typically 0.4T to 0.6T. It is. Here, T is the period of the channel clock and corresponds to the length of the 1-bit signal.
[0051]
The average energy given to the recording film by the comb pulse train 2 (= “the average value of the recording power in the mark section”) strongly depends on the duty of the comb pulse train 2. Here, the duty of the comb pulse train 2 is defined by “(pulse width of one pulse) / (pitch of the pulse train)”. The duty when the comb-shaped pulse train 2 is composed of a single short pulse can be defined as “(width of the single pulse) / (interval between the front end pulse and the rear end pulse)”. The pulse amplitude of the comb pulse train 2 used in this embodiment is the same as the amplitude of the front end pulse 1 and the rear end pulse 3. For this reason, when the duty of the comb pulse train 2 is 50%, the average energy of the comb pulse train 2 is about half of the average energy of the front end pulse 1 and the rear end pulse 3.
[0052]
When the recording film is irradiated with such recording light, the temperature of the recording film increases rapidly by the irradiation of the front end pulse 1 and then tends to decrease during the irradiation period of the comb pulse 2. If the temperature drop of the recording film is large, the phase change of the recording film can be achieved only insufficiently.
[0053]
Next, refer to FIG. FIG. 3B shows the planar shape of the three types of marks formed on the recording film of the optical disc. As shown in FIG. 3B, the longer the mark, the more likely it is that thinning is likely to occur. In the comparatively short mark 15, since the irradiation period of the comb pulse train 2 is relatively short, the thinned shape hardly occurs. However, in the case of the slightly longer mark 16, the period during which the comb pulse train 2 is irradiated becomes slightly longer, so that the average energy of the recording light starts to be insufficient during irradiation. As a result, the shape of the mark 16 tends to be thin. In the case of the long mark 18, the thinning is more remarkable. This is because in the case of the long mark 18, the ratio of the irradiation period of the comb pulse train 2 to the mark section is large, and the temperature drop of the recording film cannot be ignored.
[0054]
The length of the mark to be formed depends on the irradiation time of the recording light, the linear velocity of the recording light moving on the optical disc, and the like. Mark thinning becomes significant when the length of the mark is twice or more the spot diameter of the recording light on the recording film. Here, the spot diameter can be defined as the full width at half maximum of the intensity distribution of the recording light on the recording film.
[0055]
Hereinafter, the reason why the thinning of the mark causes an information reading error will be described with reference to FIGS. 3 (c) and 3 (d). FIG. 3C shows a waveform of a reproduction signal obtained when the mark of FIG. 3B is reproduced. FIG. 3D shows the detection of the level of the reproduction signal based on the threshold 6. The binarized signal obtained by doing is shown. In this example, the “High” portion of the binarized signal corresponds to the mark interval, and the “Low” portion of the binarized signal corresponds to the space interval.
[0056]
First, reference is made to FIG. A reproduction signal 17 having a bimodal waveform is obtained from the mark 16 having an intermediate length. However, the level of the reproduction signal 17 does not fall below the binarization threshold 6 even in the center of the mark 16. Therefore, as shown in FIG. 3D, a binary signal having a correct mark length is obtained from the mark 16.
[0057]
As shown in FIG. 3C, a sharp bimodal waveform reproduction signal 19 having a low concave portion 20 at the center is obtained from the mark 18 in which the thinning has occurred strongly. Since the level of the reproduced signal 19 in the recess 20 is lower than the threshold value 6, if the reproduced waveform 19 is binarized by the threshold value 6, two binarized values are obtained as shown in FIG. Signals, that is, the binarized signal 21 and the binarized signal 22 are generated. Since the rear end edge 37 of the binarized signal 21 and the front end edge 38 of the binarized signal 22 exist in excess, the length of the mark 18 cannot be detected correctly.
[0058]
As described above, the longer the mark, the more easily the mark becomes thinner. However, when the recording sensitivity of the optical disk to be used is good, even a long mark has a small degree of thinning, and a reading error hardly occurs.
[0059]
In conventional optical information recording / reproducing apparatuses, for the purpose of optimizing the power of recording light, marks have been recorded and reproduced on a test basis. It could not be detected separately from the error caused by the cause.
[0060]
In the present invention, after recording a relatively long test mark, it is determined whether or not the length of the long test mark can be correctly detected based on a binary signal reproduced from the test mark. In this way, it is possible to know whether or not the optical disk is easy to form a mark having a thin shape.
[0061]
[Configuration of optical recording / reproducing apparatus]
Next, an embodiment of an optical recording / reproducing apparatus according to the present invention will be described with reference to FIG. As shown in FIG. 1, the apparatus according to the present embodiment condenses light emitted from a spindle motor 24 that rotates an optical disc 23, a semiconductor laser 25 that emits a light beam that irradiates the optical disc 23, and a semiconductor laser 25. The light from the condenser lens 26, the light from the condenser lens 26 is converged on the optical disk 23 to form a light spot, the beam splitter 28 that reflects the light reflected from the optical disk 23 in the light detection direction, and the photodetector. A detection lens 29 that condenses the reflected light, a photodetector 30 that converts the reproduction light into an electrical signal, and the like are provided.
[0062]
The reproduction signal output from the photodetector 30 is amplified by the reproduction amplifier 31 and input to the waveform equalization circuit 32 that corrects the high frequency characteristics. From the waveform equalization circuit 32, a reproduction signal having a waveform as shown in FIG.
[0063]
The output from the waveform equalization circuit 32 is input to the level detection circuit 33 and binarized by the threshold value 6. When the reproduction signal 19 as shown in FIG. 3C is input to the level detection circuit 33, the level detection circuit 33 outputs binary signals 21 and 22 divided into two.
[0064]
The binarized signal output from the level detection circuit 33 is input to the PLL 34 for data clock extraction, and further converted into binary data by the demodulation circuit 35. During normal reproduction operation, this binary data is output from the demodulation circuit 35 as read data (READ DATA).
[0065]
The bit error measurement circuit 44 receives the binary data output from the demodulation circuit 35 and measures the bit error.
[0066]
The jitter measurement circuit 36 compares the front and rear edges of the pulse in the binarized signal with the clock extracted by the PLL 34 and integrates the phase shift amount. As a result, the fluctuation amount of the front / rear edge of the recording mark That is, the jitter in the mark section and the space section is measured.
[0067]
When the reproduction signals 6 and 17 shown in FIG. 3C are input to the level detection circuit 33, the measured jitter is relatively small. However, when the reproduction signal 19 having strong bimodality shown in FIG. 3C is input to the level detection circuit 33, the measured jitter increases rapidly. This is because the positions of the edges 37 and 38 shown in FIG. 3D are unspecified, and the phase difference with respect to the clock extracted by the PLL 34 becomes unspecified, resulting in an increase in jitter. Such a jitter measurement circuit is described in detail, for example, in US Pat. No. 5,663,942.
[0068]
The optical recording / reproducing apparatus receives input data (WRITE DATA), modulates it, a recording pulse generation circuit 41 that generates a recording pulse based on the output of the modulation circuit 40, and a recording pulse generation A light beam driving circuit 42 that receives the output of the circuit 41 and modulates the laser light emitted from the semiconductor laser 25 is provided.
[0069]
During normal data recording, the recording pulse generation circuit 41 generates various recording pulses according to the output from the modulation circuit 40 using information (table) stored in a nonvolatile memory (not shown). The basic values that define the waveform of each recording pulse (number of pulses in the comb pulse train, pulse width of the front end pulse, pulse width of the rear end pulse, etc.) are determined from the table according to the length of the mark to be formed. Selected. Some of these numerical values may be changed according to the front and rear space lengths.
[0070]
In addition to the above components, the optical recording / reproducing apparatus according to the present embodiment generates long mark data that generates data necessary for writing a test mark having a length longer than a selected length on a recording film. A generation circuit 39 is provided.
[0071]
The long mark data generation circuit 39 enters an active state upon receiving a data generation start signal output from the CPU in the system controller, and generates data necessary for forming a mark having a predetermined length. This long mark data generation circuit 39 generates not only data necessary for generating one fixed type of test mark but also a plurality of types of data for test marks having different lengths in accordance with instructions from the CPU. It may be configured as follows.
[0072]
In this optical recording / reproducing apparatus, marks having a plurality of lengths can be formed on a recording film of an optical disc in accordance with data to be recorded (WRITE DATA). The long mark data generation circuit 39 generates data for forming a test mark having a length that is highly likely to be thinned among the marks having a plurality of lengths. The length of the test mark may be fixed to one value when the apparatus is manufactured, or may be configured to be selected from a plurality of values.
[0073]
Data output from the long mark data generation circuit 39 is input to the recording pulse generation circuit 41. The recording pulse generation circuit 41 generates a recording pulse for forming a mark having a length corresponding to input data. When the test mark is first formed, the initial value of information defining the waveform of the recording pulse is set based on data stored in the nonvolatile memory. It is preferable that the initial setting value of the information defining the recording pulse is stored from the time of shipment in a nonvolatile memory in the optical recording / reproducing apparatus. The initial setting value may be selected based on information (control data) recorded in a special area of the optical disc.
[0074]
When conventional recording light compensation for appropriately recording short marks is performed, information defining the waveform of the compensated recording pulse is recorded on a nonvolatile memory or an optical disk in the optical recording / reproducing apparatus. When performing the recording light correction of the present invention after performing such conventional recording light compensation, the recording pulse used when forming the first test mark is the recording after compensation by the conventional recording light compensation. It is preferable to use a pulse.
[0075]
After performing the recording light correction of the present invention, information (correction information) necessary for defining the corrected recording pulse is preferably recorded in a nonvolatile memory or an optical disk in the apparatus. This is because, when the optical disk is once taken out from the apparatus and then loaded again into the apparatus, the recording pulse waveform can be defined for the long mark using the previous correction information as an initial set value. If the previous final correction information is used for the initial setting of the current correction, the time required for the correction can be shortened.
[0076]
This optical recording / reproducing apparatus has a mark width determination processing circuit 43 configured by a program type data processing circuit including a CPU and a memory in a system controller. The mark width determination processing circuit 43 receives the output of the jitter measurement circuit 36 and / or the output of the bit error measurement circuit 44, and executes a process of determining whether or not the test mark is excessively thinned. The program type data processing circuit may not only perform the process of determining whether the long mark is thin, but may control operations such as recording / reproduction timing switching control according to a program.
[0077]
Hereinafter, an operation for recording the test mark on the optical disc by the optical recording / reproducing apparatus and an operation for determining whether or not the test mark has a thin shape will be described.
[0078]
First, when the optical disk 23 is loaded in the optical recording / reproducing apparatus, a known recording light power compensation operation is started, and the power of the recording light is adjusted so that a short mark can be appropriately written. Thereby, the peak power (Pp), bias power 1 (Pb1), and bias power 2 (Pb2) of the recording light are set. After such a compensation operation is completed, the operation of the long mark data generation circuit 39 that has received the data generation start signal from the system controller starts, and the recording pulse generation circuit 41 generates a recording pulse for the test mark. The generated recording pulse is input to the light beam driving circuit 42 so that the power of the recording light is modulated between three levels of peak power (Pp), bias power 1 (Pb1), and bias power 2 (Pb2). The semiconductor laser 25 is driven. The optical disk 23 is irradiated with recording light emitted from the semiconductor laser 25, and a test mark is recorded on the recording film.
[0079]
Next, the test mark recorded on the optical disc 23 is reproduced. When the test mark is reproduced, the jitter of the reproduced signal is measured by the jitter measuring circuit 36. The measured jitter numerical data is transmitted to the mark width determination processing circuit 43. The mark width determination processing circuit 43 compares the jitter numerical data transmitted from the jitter measurement circuit 36 with a pre-programmed reference jitter. When the measured jitter is larger than the reference jitter, the mark width determination processing circuit 43 determines that the recorded test mark has a thin shape. In other words, it is detected that there is a portion in the test mark where the change in optical characteristics is not sufficient for reading the test mark (read error inducing portion).
[0080]
Whether or not the recorded test mark has a thin shape is determined by measuring the bit error rate of the demodulated binary data output from the demodulation circuit 35 by the bit error measurement circuit instead of measuring the jitter. It is also possible.
[0081]
Hereinafter, an example in which the thinness of the test mark is detected by measuring the bit error rate will be described.
[0082]
When the binarized signals 21 and 22 shown in FIG. 3D are demodulated by the demodulation circuit 35, the binary data is not correctly demodulated and incorrect binary data is output. This erroneous binary data and the recording source data generated by the long mark data generating circuit 39 are compared by the bit error measuring circuit 44, and a bit error which is the ratio of the erroneous data is output.
[0083]
This bit error is transmitted to the mark width determination processing circuit 43 and compared with a pre-programmed reference bit error. When there are more data errors than reference bit errors, the mark width determination processing circuit 4 determines that the recorded test mark has a thin shape.
[0084]
In the above example, whether or not the test mark has a thin shape is determined based on jitter or bit error. Instead, it is performed based on the test mark length measurement. May be. FIG. 9 is a block diagram showing another embodiment of the present invention including a long mark pulse width count circuit 90 connected to the output of the demodulation circuit 35 and the output of the PLL 34. The long mark pulse width count circuit 90 receives the binary data output from the demodulation circuit 35 and the clock sent from the PLL 34, and counts the number of clocks corresponding to the length of the test mark. When a strong thinning occurs in a test mark of the original length L (corresponding to the number of clocks m), the length (number of clocks) of the binary data reproduced from the one test mark is the original correct clock number m. Will have different values. This also makes it possible to detect the thinness of the test mark.
[0085]
[Power correction of recording light]
When thinning of a long test mark is detected by the method described above, it is necessary to correct the power of the recording light. When the recording light power is corrected by the conventional method described with reference to FIG. 2, both the mark width and the mark length are increased, and the correction may be adversely affected.
[0086]
Hereinafter, a new method for correcting the recording light power employed in the present invention will be described with reference to FIGS.
[0087]
First, it is assumed that the test mark 4 having a strongly thinned shape shown in FIG. 4B is formed by using the recording pulse shown in FIG. The signal 5 reproduced from the test mark 4 has a bimodal waveform as shown in FIG. When the reproduction signal 5 is binarized by the threshold value 6, a binarized signal divided into two pulses 7 and 8 is obtained as shown in FIG.
[0088]
In the first correction method according to the present invention, the duty of the comb pulse train 45 is increased as shown in FIG. Since the thinning of the mark 4 is caused by the lack of thermal energy in the comb pulse train 2, the average thermal energy can be increased by increasing the pulse width or duty of the comb pulse train 2. In this case, the shortage of heat energy can be solved.
[0089]
Employment of the comb pulse train 45 having a large pulse width or duty forms a mark 46 having a uniform width as shown in FIG. When this mark 46 is reproduced, a reproduction signal 47 as shown in FIG. 4C is formed. An appropriate binarized signal 48 is obtained from the reproduction signal 47 as shown in FIG.
[0090]
In the second correction method of the present invention, as shown in FIG. 4A, the bias power 2 (Pb2) is increased to the bias power 22 (Pb22). Increasing the bottom value power of the comb pulse train can solve the shortage of thermal energy.
[0091]
Employment of recording light having increased bias power 22 (Pb22) forms a mark 49 having a uniform width as shown in FIG. 4B. When this mark 49 is reproduced, a reproduction signal 50 as shown in FIG. 4C is formed. From the reproduction signal 50, an appropriate binarized signal 51 is obtained as shown in FIG.
[0092]
As described above, the width of the recording mark is made uniform by changing the pulse width (duty) of the comb pulse train 2 from the initial setting value or by changing the bottom value power of the comb pulse train 2. be able to.
[0093]
Thus, in the present invention, the radiation energy given to the front end portion and the rear end portion of the mark is not substantially increased, and the radiation energy given to the region (intermediate region) sandwiched between the front end portion and the rear end portion of the mark is substantially increased. Increase partially. As a result, the cause of mark thinning (insufficient thermal energy) can be removed, and the mark width can be made uniform effectively. Such a correction method of the recording light power is not limited to the method described above. The long mark may be recorded using a recording pulse in which the power of the comb pulse train 2 is larger than the power of the front end pulse 1 or the rear end pulse 3.
[0094]
[Correction process 1]
Next, the procedure of the process for correcting the energy of the recording light by changing the pulse width or duty of the comb pulse train 2 will be described in detail with reference to FIG.
[0095]
The correction process executed in the present invention is preferably performed every time the optical disk is transferred to the optical recording / reproducing apparatus. However, it is preferable that a known recording light power compensation operation is performed after the optical disc is placed on the recording / reproducing apparatus and before the correction operation according to the present invention is performed.
[0096]
When a known recording light power compensation operation is performed, a relatively short mark is reproduced after being written on the recording film as a test. Then, the power of the recording light is compensated so that the reading error is reduced. This compensation is first executed by multiplying the entire recording light power by α as shown in FIG. After the amplitude of the recording light power is determined, the pulse widths of the front end pulse and the rear end pulse are optimized. In this recording light power compensation operation, the first test mark is written on the recording film using the recording pulse determined by the recording pulse generation circuit 41 based on the initial setting data. As the initial setting data, parameter data stored in advance on the optical disc or parameter data stored in a memory in the optical recording / reproducing apparatus can be used.
[0097]
The recording light power compensation operation described above is performed in order to appropriately record a relatively short mark. In the present embodiment, however, power correction for appropriately recording a relatively long mark is performed thereafter. Hereinafter, this power correction will be described.
[0098]
First, in step 52, a test mark having a length longer than a selected length is recorded on the optical disc. This test mark is preferably recorded in a test area provided in the inner circumference or outer circumference area of the optical disc.
[0099]
Next, in step 53, the test mark is reproduced. Then, at step 54, jitter or bit errors are measured. Next, in step 55, it is determined whether the jitter is less than the reference jitter A or whether the bit error is less than the reference bit error A. As a result of the determination, if the jitter is smaller than the reference jitter A, or if the bit error is smaller than the reference bit error A, the correction process is terminated because it is not necessary to correct the power of the recording light.
[0100]
If the result of determination is that the jitter is greater than or equal to the reference jitter A, or if the bit error is greater than or equal to the reference bit error A, the process moves to step 56.
[0101]
In step 56, the recording light power described above is corrected. For example, the duty of the comb pulse train 2 is increased by one unit. Increasing the duty by one unit corresponds to increasing each pulse width of the comb pulse train 2 by 1 nanosecond, for example. The bottom power Pb2 of the comb pulse train 2 may be increased by one unit. Increasing the bottom power by one unit corresponds to increasing the bottom power by 1 mW, for example.
[0102]
In step 57, a test mark is recorded with recording light having a corrected waveform.
[0103]
In step 58, the test mark is reproduced.
[0104]
In step 59, jitter or bit error is measured for this test mark.
[0105]
In step 60, it is determined whether the measured jitter is less than the reference jitter B or whether the measured bit error is less than the reference bit error B. If the result of the determination is that the measured jitter is less than the reference jitter B, or if the measured bit error is less than the reference bit error B, the correction process ends.
[0106]
The reference jitter B used in step 60 is preferably set to be equal to or lower than the reference jitter A in step 55. This is because, when the correction process is performed again on the same optical disk, the time required for the correction process is shortened by ensuring that the correction jitter is lower than the reference jitter A. Similarly, the reference bit error B used in step 60 is preferably set equal to or lower than the reference bit error A in step 55 described above.
[0107]
If the result of determination in step 60 is that the measured jitter is greater than or equal to reference jitter A, or if the measured bit error is greater than or equal to reference bit error A, the process returns to step 56 again. Then, the duty of the comb pulse train 2 is increased by one unit, or the bottom power Pb2 of the comb pulse train 2 is increased by one unit.
[0108]
As described above, the algorithm of the correction method shown in FIG. 5 has a loop for measuring jitter or bit error each time the power of the recording light is corrected.
[0109]
Next, the relationship between the jitter or bit error and the duty or bottom power of the comb pulse will be described with reference to FIG. The horizontal axis in FIG. 6 indicates the amount of duty or bottom power of the comb pulse, and the vertical axis indicates the jitter or bit error value of the long mark recorded under the conditions of the horizontal axis.
[0110]
In FIG. 6, the initial value of the duty or bottom power of the comb pulse when the test mark is recorded for the first time is indicated by point c. The initial value of jitter or bit error at this time is indicated by point C.
[0111]
Since the jitter or bit error value at point C is higher than the reference jitter A or the reference bit error A, correction is performed by increasing the duty or bottom power of the comb pulse so that the jitter or bit error value becomes lower. . A state where the duty or bottom power of the comb pulse is increased by one unit is the n1 point. In this state, it is still higher than the reference jitter B or the reference bit error B. Further, the states increased by one unit are n2, n3, and n4 points. Correction and measurement are repeated sequentially at each point, and the correction ends because the value of jitter or bit error is lower than the reference jitter B or reference bit error B at the point n4.
[0112]
[Correction process 2]
Next, another procedure for correcting the energy of the recording light will be described with reference to FIG.
[0113]
First, in step 61, a test mark having a length longer than a certain length is recorded in the test area of the optical disc. In step 62, the test mark is reproduced. Then, at step 63, jitter or bit error is measured. Next, at step 64, it is determined whether the jitter is less than the reference jitter A or whether the bit error is less than the reference bit error A. As a result of the determination, if the jitter is smaller than the reference jitter A, or if the bit error is smaller than the reference bit error A, the correction process is terminated because it is not necessary to correct the power of the recording light.
[0114]
If the result of determination is that the jitter is greater than or equal to the reference jitter A, or if the bit error is greater than or equal to the reference bit error A, the process moves to step 65. In step 65, the recording light power described above is corrected. For example, the duty of the comb pulse train 2 is increased by one unit. The bottom power Pb2 of the comb pulse train 2 may be increased by one unit.
[0115]
In step 66, a long mark is recorded using the corrected recording pulse, and in step 67, the number of correction recordings is counted. Step 65 is repeated until the count value becomes N (N is an integer of 2 or more). N represents the number of different conditions of the recording light. Test marks may be written on the N recording tracks using recording light with different corrections. When the recording light power is corrected by increasing the duty of the comb pulse train 2 by one unit, N is set to an appropriate value within a range until the duty of the comb pulse reaches 100%. When correcting the power of the recording light by increasing the bottom power Pb2 of the comb pulse train 2 by one unit, N is set to an appropriate value within a range until the bottom power becomes equal to the peak power. As N, for example, a number from 5 to 10 is selected.
[0116]
When the count value becomes N in step 67, the process proceeds to the next step 68. In step 68, the N types of long marks recorded in steps 65, 66, and 67 are sequentially reproduced.
[0117]
In step 70, it is determined whether the jitter measured in step 69 is less than the reference jitter B or whether the measured bit error is less than the reference bit error B. If the result of the determination is that the measured jitter is less than the reference jitter B, or if the measured bit error is less than the reference bit error B, the correction process ends.
[0118]
The reference jitter B used in step 70 is preferably set to be equal to or lower than the reference jitter B in step 64. This is because when the correction process is performed again on the same optical disc, the time required for the correction process is shortened by ensuring that the correction jitter is lower than the reference jitter B. Similarly, the reference bit error B used in step 70 is preferably set equal to or lower than the reference bit error A in step 64 described above.
[0119]
If the result of determination in step 70 is lower than the reference jitter B or lower than the reference bit error B, it is determined that the recording mark width has been made uniform by the correction, and this correction step is terminated.
[0120]
If the result of determination in step 70 is that the measured jitter is greater than or equal to reference jitter A, or the measured bit error is greater than or equal to reference bit error A, the process returns to step 68 again. Then, the track of the next recording condition in which the duty of the comb-shaped pulse train 2 is increased by 1 unit or the bottom power Pb2 of the comb-shaped pulse train 2 is increased by 1 unit is reproduced to be lower than the reference jitter B or the reference bit error Repeat steps 68, 69, and 70 until B is lower.
[0121]
In this way, in the process shown in FIG. 7, after N types of test marks having different recording conditions are recorded in the test area in advance, these N types of test marks are sequentially reproduced to measure jitter or bit error. To do. N types of test marks may be formed on different tracks.
[0122]
Next, the relationship between the jitter or bit error and the duty or bottom power of the comb pulse will be described with reference to FIG. The horizontal axis in FIG. 8 indicates the amount of duty or bottom power of the comb pulse, and the vertical axis indicates the jitter or bit error value of a long mark recorded under the conditions of the horizontal axis.
[0123]
The initial value of the duty or bottom power of the comb pulse when the long mark is recorded under the initial conditions corresponds to the point c. The initial value of jitter or bit error at this time is point C.
[0124]
Since the jitter or bit error value at the point C is larger than the reference jitter A or the reference bit error A, the duty or bottom power of the comb pulse is increased so that the jitter or bit error value becomes smaller. In FIG. 8, test marks having different recording conditions are formed by increasing the duty or bottom power of the comb pulse by one unit. A total of N types of test marks are recorded from n = 1 to n = N. If the test mark recording conditions are changed for each track, N types of recording conditions can be made to correspond to N tracks.
[0125]
Next, tracks having different recording conditions are sequentially reproduced from n = 1, and the jitter or error rate is measured. When reproduction and measurement are repeated, the jitter or bit error value measured at the point n = M falls below the reference jitter B or the reference bit error B. The power of the recording light may be corrected based on the recording conditions at this time.
[0126]
As described above, according to the present invention, when a test mark having a thin shape is detected, the step of correcting each pulse width of the comb pulse train 2 or the bottom value power of the comb pulse train 2 is corrected. By executing the process, the mark width can be made uniform.
[0127]
[DVD-RAM]
The optical recording / reproducing apparatus according to the present invention is preferably used when information is recorded on an optical disc according to the DVD-RAM standard and information is reproduced from such a disc.
[0128]
In the DVD-RAM standard, 8/16 modulation recording coding system is adopted, and 9 types assigned to 9 types of NRZI (Non Return to Zero Inverted) signals each having a length of 3T, 4T,. A recording mark having a length of is formed. Here, T is the period of the channel clock and corresponds to the length of the 1-bit signal. In this case, the maximum length of the plurality of marks associated with the information to be recorded is expressed as “11T”, and the minimum length is expressed as “3T”. When a mark is written on a recording film with a laser beam having a power compensated using a conventional recording power compensation method, the mark having a length of 6T or less is hardly thinned. For this reason, the length of the test mark is preferably 7T or more. Since the mark that is most likely to be thinned is a mark having a length of 11T, it is most preferable to set the length of the test mark to 11T.
[0129]
For example, when an 11T mark is formed as a test mark and the recording light power correction is performed thereby, the correction result need not be applied to all marks having a length of 3T, 4T,. For example, the recording light power correction may be performed only when a mark having a length of 7T or more, that is, a mark having a length of 7T, 8T, 9T, 10T, and 11T is formed. In this case, the same degree of correction may be executed for each of the marks 7T to 11T, but the degree of correction may be changed according to the length of the mark. For example, when forming marks of 7T to 9T, the duty of the comb pulse train 2 is 51%, and when forming 10T and 11T marks, the duty of the comb pulse train 2 is 53%. good.
[0130]
When the 8/16 modulation recording encoding method is employed, an example of the long mark data generation circuit 39 in FIG. 1 is configured as shown in FIG.
[0131]
The long mark data generation circuit 39 includes a counter 81, a decoder 82, and a preset circuit 83. The counter 81 counts the number of input clocks and sends, for example, a count value expressed by a 5-bit signal to the decoder 82. A preset circuit 83 is connected to the decoder 82. The preset circuit 83 generates count value data corresponding to the lengths of 9T, 10T, and 11T, for example, in accordance with a command from the CPU, and transmits the count value data to the decoder 82. The decoder 82 compares the count value data from the preset circuit 83 and the count value from the counter 81, and outputs a pulse having a pulse width corresponding to the matched count value. As a result, the decoder 82 outputs data corresponding to a mark / space having a length of 11T, for example.
[0132]
An example of the long mark pulse width count circuit 90 of FIG. 9 is configured as shown in FIG.
[0133]
The long mark pulse width count circuit 90 includes a counter 91 and a data latch circuit 92. The binary data output from the demodulation circuit is input to the SET terminal (S) of the counter 91 via an inverter. On the other hand, the binary data output from the demodulation circuit 35 is input to the RESET terminal (R) of the counter 91 as it is. A clock signal from the PLL 34 is input to the clock terminal of the counter 91. The counter 91 counts the number of clocks from the rising edge to the falling edge of the binary data output from the demodulation circuit 35 and sends the count value to the data latch circuit 92. The data latch circuit 92 latches and outputs the output (count value) of the counter 91 in response to the falling edge of the binary data output from the demodulation circuit 35.
[0134]
FIG. 12 is a timing chart showing the demodulation circuit output, clock, count value, and data latch circuit output.
[0135]
In this case, the mark width determination processing circuit 43 is configured to determine whether the data reproduced from the test mark has a correct length based on the output of the data latch circuit 92.
[0136]
In these examples, the case where the 8/16 modulation recording encoding method is employed has been described. However, the effect of the present invention is sufficient even when data recording / reproduction is performed using another recording encoding method. It goes without saying that you can get it.
[0137]
As mentioned above, although the present invention has been described with respect to the embodiment of the apparatus for recording / reproducing information with respect to the phase change recording medium, the present invention is not limited to this. The present invention can also be applied to, for example, an apparatus for recording / reproducing information with respect to a magneto-optical recording medium. In that case, at least a part of the recording film of the recording medium to be used is formed of a magnetic material, and the recording film changes its optical characteristics (Kerr rotation angle etc.) by both application of a magnetic field and irradiation of a light beam. become.
[0138]
Note that the present invention is not limited by the waveform of the recording light employed in the embodiment. The amplitude of the comb pulse train may be set to be different from the amplitudes of the front end pulse and the rear end pulse. Further, some pulses in the comb pulse train may have different amplitudes or different widths from other pulses in the comb pulse train.
[0139]
【The invention's effect】
In the present invention, in an optical recording / reproducing apparatus capable of forming a plurality of marks having different lengths on a recording film of a recording medium, recording of a relatively long test mark having a length longer than a selected length -The power of the light beam is corrected so that the width of the long mark is made uniform by performing the reproduction specially. For this reason, according to the present invention, it is possible to reliably suppress thinning that tends to occur in long marks, and to reduce reading errors even when the sensitivity of the recording medium is low.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of an optical recording / reproducing apparatus according to the present invention.
FIG. 2 is a diagram showing a relationship between a mark shape and a signal waveform when recording / reproducing is performed by a conventional optical recording / reproducing apparatus. (A) is a figure which shows the waveform of a recording pulse, (b) is a figure which shows the shape of the mark formed in the recording film, (c) is a figure which shows the waveform of a reproduction signal, (d) These are figures which show the waveform of the binarization signal formed from the reproduction signal.
FIG. 3 is a diagram showing a relationship between a mark shape and a signal waveform or the like when recording / reproducing is performed by an optical recording / reproducing apparatus before correcting recording light power. (A) is a figure which shows the waveform of a recording pulse, (b) is a figure which shows the shape of the mark formed in the recording film, (c) is a figure which shows the waveform of a reproduction signal, (d) These are figures which show the waveform of the binarization signal formed from the reproduction signal.
FIG. 4 is a diagram showing a relationship between a mark shape and a signal waveform when recording / reproducing is performed by the optical recording / reproducing apparatus according to the present invention. (A) is a figure which shows the waveform of a recording pulse, (b) is a figure which shows the shape of the mark formed in the recording film, (c) is a figure which shows the waveform of a reproduction signal, (d) These are figures which show the waveform of the binarization signal formed from the reproduction signal.
FIG. 5 is a flowchart showing a recording light power correction operation executed by the optical recording / reproducing apparatus according to the present invention.
6 is a graph schematically showing a change in reproduction characteristics in the correction operation of FIG.
FIG. 7 is a flowchart showing another recording light power correction operation executed by the optical recording / reproducing apparatus according to the present invention.
8 is a graph schematically showing a change in reproduction characteristics in the correction operation of FIG.
FIG. 9 is a diagram showing another configuration example of the optical recording / reproducing apparatus according to the present invention.
10 is a diagram showing a configuration example of a long mark data generation circuit 39. FIG.
11 is a diagram showing a configuration example of a long mark pulse width count circuit 90. FIG.
12 is a timing chart for explaining the operation of the long mark pulse width count circuit 90. FIG.
[Explanation of symbols]
1 Front end pulse
2 Comb pulse train
3 Rear end pulse
4 Medium thin mark
20 Optical disc
33 level detection circuit
36 Jitter measurement circuit
39 Long mark data generation circuit
41 Recording pulse generation circuit
42 Light beam drive circuit
43 Mark width judgment processing circuit
44 bit error measurement circuit
52 Long mark recording process
53 Long mark regeneration process
54 Long mark jitter or error rate measurement process
55 Reference jitter or reference error rate comparison process
56 Comb type pulse variable process
57 Correction length mark recording process
58 Correction length mark regeneration process
59 Correction length mark jitter or error rate measurement process
60 Correction reference jitter or reference error rate comparison process
90 long mark pulse width count circuit

Claims (25)

A recording film of a recording medium is irradiated with a pulsed light beam to locally change the optical characteristics of the recording film, thereby forming a plurality of marks associated with information to be recorded on the recording film. An optical recording / reproducing apparatus capable of
Information writing means for generating a recording pulse for forming the mark and modulating the light beam by the recording pulse;
Information reproducing means for detecting a change in optical characteristics of a portion including the mark formed on the recording film;
A long mark data generating circuit for writing at least one test mark having a length equal to or longer than a selected length on the recording film by the information writing unit;
A mark width determination processing circuit for determining whether or not there is a read error inducing portion in the test mark where the change in the optical characteristics is not sufficient for reproduction of the test mark;
With
When it is determined that the read error inducing portion exists in the test mark, an average value of the power of the light beam is set to an initial setting level when forming a mark having a length at least longer than the length of the test mark. An optical recording / reproducing apparatus for correcting the power so that the read error inducing portion does not occur in the mark. The optical recording / reproducing apparatus according to claim 1 , wherein the power correction is executed by partially increasing the power of the light beam at a central portion of a mark to be formed. The information writing means generates two or more pulses including a front end pulse and a rear end pulse spaced from the front end pulse as a recording pulse for forming each mark, and the length of the mark is 3. The optical recording / reproducing apparatus according to claim 1 , wherein the optical recording / reproducing apparatus depends on the number of pulses. The optical recording / reproducing apparatus according to claim 3 , wherein the power correction is performed by changing an amplitude of at least one pulse positioned between the front end pulse and the rear end pulse. The optical recording / reproducing apparatus according to claim 3 , wherein the power correction is performed by changing a duty of at least one pulse positioned between the front end pulse and the rear end pulse. Includes a memory for storing information defining the power, after completing the correction of the power, optical according to any one of claims 1 to 5 for storing information defining the power after the correction in the memory Recording and playback device. 4. The optical recording / reproducing apparatus according to claim 3 , wherein after the recording medium is loaded, the power compensation and the width compensation of the front and rear end pulses are executed, and the power correction is executed after the compensation is completed. . Among the plurality of marks associated with the information to be recorded, only when forming a mark or a length, according to any one of claims 1 to 7 using a light beam having a power of the corrected Optical recording / reproducing device. The test mark, the optical recording and reproducing apparatus according to any one of claims 1 having the maximum length and minimum length average value over the length of the plurality of marks to be formed during the data writing 8. The test mark, the optical recording and reproducing apparatus according to any one of claims 1 to 9 with a 7T or longer in 8/16 modulation scheme. The test mark, the optical recording and reproducing apparatus according to any one of claims 1 to 9 having a length of 11T at the 8/16 modulation scheme. After loading the recording medium, a test mark having a length of 6T or less in the 8/16 modulation system is formed to perform the power compensation and the front end and rear end pulse width compensation, and the compensation after completing the optical recording reproducing apparatus according to any one of claims 1 to 11 for performing the correction of the power. The mark width determination processing circuitry, based on said jitter of the mark edge obtained from the reproduction signal of the test mark, of claims 1 to 12, wherein the test mark the reading error induced part in it is determined whether there The optical recording / reproducing apparatus according to any one of the above. The mark width determination processing circuitry, based on said bit error amount obtained by demodulating the reproduced signal of the test mark, claim 1 to determine whether the read error induced portion in said test mark is present an optical recording reproducing apparatus according to any one of 13. The mark width determination processing circuit determines whether or not the reading error inducing portion exists in the test mark based on a measured value of a mark length obtained by demodulating a reproduction signal of the test mark. Item 15. The optical recording / reproducing apparatus according to any one of Items 1 to 14 . The read error induced portion, the reproduced signal level is relatively low, as a result, claim 1 in which a single test mark is binarized by mistake to include two or more marks 15 An optical recording / reproducing apparatus according to any one of the above. The information writing means includes a light beam driving circuit for driving a light source for the light beam, and a recording pulse generating circuit connected to the light beam driving circuit,
Wherein the recording pulse generation circuit, a recording pulse is generated based on the information defining the waveform of the recording pulse, the optical recording and reproducing apparatus according to any one of claims 1 to 15 to be supplied to the light beam driving circuit. 18. The optical recording according to claim 17 , wherein the long mark data generation circuit causes the recording pulse generation circuit to generate a recording pulse for the test mark based on information defining a recording pulse for the test mark. Playback device. The optical recording / reproducing apparatus according to claim 17 , further comprising a non-volatile memory storing information defining a waveform of the recording pulse. The optical recording / reproducing apparatus according to claim 17 , further comprising a memory area in which information necessary for defining the corrected recording pulse is stored. The information reproducing means includes
An optical system for irradiating the recording medium with reproduction light;
A photodetector that receives the reproduction light reflected from the recording medium and converts it into an electrical signal;
An optical recording reproducing apparatus according to any one of claims 1 to 15, and a circuit for generating binary data on the basis of the signal output from the photodetector. A recording film of a rewritable recording medium is irradiated with a pulsed light beam to locally change the optical characteristics of the recording film, whereby a plurality of marks associated with information to be recorded are recorded on the recording film An optical recording / reproducing apparatus that can be formed into
Writing to the recording film at least one test mark having a length greater than or equal to a selected length;
Detecting a change in optical characteristics of a portion including the test mark in the recording film;
Performing a test recording operation including determining whether there is a read error inducing portion in the test mark where the change in the optical characteristics is not sufficient for reproduction of the test mark;
When it is determined that the read error inducing portion exists in the test mark, an average value of the power of the light beam is set to an initial setting level when forming a mark having a length at least longer than the length of the test mark. An optical recording / reproducing device that increases from When it is determined that the read error inducing portion exists in the test mark, another recording mark is placed on the recording film by using the light beam whose average power is increased from a certain setting level to the next setting level. And then determining whether the read error inducing portion is present in the test mark,
The optical recording / reproducing apparatus according to claim 22 , wherein at least once is executed. When it is determined that the read error inducing portion exists in the test mark, N types (N is 2) are used by using the light beam in which the average value of power is increased from a certain setting level to a plurality of different setting levels. A step of determining whether or not the read error inducing portion is present in any of the test marks,
The optical recording / reproducing apparatus according to claim 22 , wherein at least once is executed. Wherein before the test mark to perform the step of writing to the recording layer, an optical recording reproducing apparatus according to any one of 24 claims 22 to perform compensation of the power of the light beam with respect to a mark shorter than the test mark.

Images