JP4538362B2 - Information recording device - Google Patents

Description

  The present invention relates to an information recording apparatus for recording information by injecting energy into a recording medium to form a mark having a physical property different from that of an unrecorded portion, and relates exclusively to an optical disc apparatus.

  Currently available optical disks are a magneto-optical disk that forms marks by reversal magnetic domains on the recording film by heating the recording film, and the cooling rate of the recording film is changed by controlling the amount of energy input during heating. The phase change disk can be roughly classified into a phase change disk in which a mark formed of an amorphous region is formed on the recording film. In order to improve the information transfer speed at the time of recording / reproducing in these optical discs, there are methods of increasing the recording linear density or increasing the scanning speed of the recording medium by the light spot. In order to increase the recording linear density, in addition to reducing the mark and space length itself, there is a method of shortening the mark edge and space length increments and reducing the time width for detecting the mark edge position. However, in the method of increasing the recording linear density, the signal-to-noise ratio in the reproduced signal becomes a problem, and it is impossible to expect a significant increase in the recording linear density.

  For the purpose of forming a highly accurate minute mark on an optical disk, the first prior art described in Japanese Patent Laid-Open No. 5-298737 corresponds to the recording waveform corresponding to the mark formation period corresponding to the mark length of the recording code string. A method for controlling the number and amplitude of each pulse in accordance with the length of the recording code string is disclosed. The recording waveform during the mark formation period is divided into two parts, a head part and a subsequent part, and the pulse height of each pulse is generally different. Further, during the mark non-formation period of the recording waveform, a recording assist pulse is generated with a space portion in front. As described above, in the first prior art publication, it is possible to compensate the thermal diffusion from the preceding mark formation portion to the front edge position of the immediately following mark regardless of the space length, and to increase the mark width and the mark edge position. It can be controlled accurately. Here, the mark formation period reflects the length of the mark in the recording code string, and as shown in FIG. 3, a pulse having an energy level for supplying recording energy necessary for forming a certain single mark, Defined as from the rising edge of the first pulse to the falling edge of the last pulse of a pulse having an energy level at which no mark is formed unless an energy level is generated. The mark non-formation period reflects the length of the space in the recording code string and is defined as a period other than the mark formation period. The above definition is common to the description in this specification.

  In the second prior art described in JP-A-8-7277, each recording code is divided into a plurality of basic elements having different lengths, and one recording pulse is associated with each element. Is formed as a series of independent recording marks by each recording pulse. In the second prior art gazette, even if an independent mark is recorded by this method, the reproduction signal level does not decrease, and stable recording can be performed even in a modulation system including a long mark. Furthermore, in the rewritable recording medium, it is said that an increase in the jitter of the reproduced signal after being rewritten many times can be suppressed.

  Further, in the third prior art described in Japanese Patent Laid-Open No. 9-134525, a multi-pulse recording system comprising a leading heating pulse, a plurality of trailing heating pulses, a trailing cooling pulse, and a trailing cooling pulse is used. A method is disclosed in which the pulse width of the rear heating pulse and the rear cooling pulse is made substantially the same as the recording channel clock cycle when recording the even mark length or odd mark length with respect to the channel clock cycle. . In the third prior art gazette, the method can secure a sufficient cooling time of the recording medium, and enables accurate edge position control.

  Other examples relating to waveform control include Japanese Patent Laid-Open Nos. 55-139893 and 61-237233.

JP-A-5-298737

  In the first prior art, one recording pulse corresponds to the extension of the mark corresponding to the detection window width. For this reason, when the detection window width is shortened, it becomes necessary to drive the semiconductor laser diode, which is a recording energy generation source, at a higher speed than before. For example, when a general (1,7) modulation method is used to achieve a burst transfer rate of 10 MBytes / sec, which is the same as that of a magnetic disk device, the detection window width in the reproduction signal is about 8.3 ns, and therefore the shortest recording time The current pulse width is about 4.2 ns, which is about 1/2 of the detection window width. However, it takes about several ns for the semiconductor laser to rise, and it is difficult to generate a precise recording light pulse. Even if an accurate recording light pulse can be generated, when the multi-pulse recording is performed on a medium that controls the formation of the mark by the cooling rate of the heated part such as a phase change disk, the heated part is sufficient. Since the next light pulse is irradiated before cooling, normal mark formation becomes impossible. For example, similarly, when trying to realize a burst transfer rate of 10 Mbytes / sec using the (1,7) modulation method, the cooling time of the recording medium is about 4.2 ns, which is equal to the shortest recording current pulse width. Marks cannot be formed correctly depending on the characteristics of the medium.

In the second prior art, each recording code is divided into a plurality of basic elements having different lengths, one recording pulse is made to correspond to each element, and each recording code is made independent by each recording pulse. A method for forming a series of recording marks is disclosed.
However, in this prior art, the thermal balance between the recording pulses corresponding to each element is not considered, and when the recording linear density is increased, there is a problem in the control of the mark edge position. That is, when a mark corresponding to one recording code is to be formed, the amount of heat accumulated in the recording film is different between the recording code head and the recording code rear end, so the recording mark width varies depending on the position, and the accurate Edge recording is not possible.

  In the third prior art, there is a case where a pulse considerably shorter than the detection window width is inserted in the recording waveform near the center of the mark formation period, and the mark width in the vicinity thereof is larger than that in other portions. fluctuate. In the description of the prior art, when mark / edge recording is performed, if the mark edge position is accurate, the fluctuation of the signal amplitude at the center of the mark is not a big problem. However, in the case of a recording / reproducing apparatus that determines the recording / reproducing conditions by detecting the average level of the reproduced signal, such distortion of the reproduced signal adversely affects the operation of the apparatus. For example, in the case of a phase change recording medium, a signal can be detected by a change in reflectance as in the case of a phase pit type recording medium. For this reason, the phase change recording medium has an advantage that the phase pit type recording medium and the reproducing apparatus can be easily used. However, the reproduced signal from the phase pit type recording medium does not have the above-described distortion. Playback with the same device becomes difficult.

  Therefore, as described above, in each of the above prior arts, marks cannot be formed with sufficient accuracy at a high transfer speed, and as a result, sufficient recording surface density and reliability cannot be realized.

  In order to stably form marks and perform highly reliable recording and reproduction, a recording waveform that does not cause the above-described problem must be selected. The conditions required for the recording waveform include the following two points in addition to the ability to form marks with high accuracy. That is, the first is that the semiconductor laser as the light source can be driven easily, and the second is that a sufficient cooling time can be secured for the recording medium.

Therefore, in order to solve the above-mentioned problem , information is recorded in an information recording apparatus that records information with information at an edge by injecting a plurality of pulsed energy into a recording medium to form a recording mark. Encoding means for converting to a string; classification means for classifying the mark length in the recording code string into an odd multiple and an even multiple with respect to the detection window width Tw; and energy generation for generating energy required for recording And every time the mark length in the recording code string increases by 2 Tw, the number of pulses of the implantation energy within the mark formation period is increased by one, and the classification means performs the odd multiple and the even multiple. Drive means for driving the energy generating means so that the recording waveforms differ according to the classification result of And the shape of the recording waveform of the even-numbered mark formation leading portion is different from the first power level to the second power level. The shape of the recording waveform of the other mark formation head portion is raised from the first power level to the second power level and held, and then the first and the second are formed. A period during which the recording waveform at the head of the other mark formation is held at the second power level after being held at the third power level between the second power levels. And the period held at the third power level is configured to be longer than the period held at the second power level of the recording waveform of the one mark formation head portion.

  As a result, the cooling time of the recording medium can be secured sufficiently, or the frequency component of the laser drive current is reduced, so that marks can be formed with sufficient accuracy even at high transfer speeds, and sufficient recording surface density And reliability can be realized.

  According to the present invention, in an information recording apparatus for recording information by injecting energy into a recording medium to form a mark having a physical property different from that of an unrecorded portion, it is possible to form a mark with high accuracy at high speed. . This makes it possible to use a mark / edge recording method that is advantageous for increasing the recording linear density as a recording method. As described above, the recording / reproducing operation can be speeded up and highly reliable, and at the same time, the information recording apparatus and the recording medium can be miniaturized, which is advantageous in terms of cost.

  Hereinafter, examples of embodiments of the present invention will be described. In this embodiment, a magneto-optical recording medium will be described as an example of a recording medium. However, this does not limit the recording medium. Marks having physical properties different from those of unrecorded portions are injected by injecting energy into the recording medium. This is a technique common to recording media (for example, phase change recording media) that record information by forming.

  In the following embodiments, the recording energy level means an average energy level over a period of about ½ times the detection window width (unit of change in edge position of mark or space). When a frequency component that is sufficiently higher than the frequency of the period corresponding to the detection window width is superimposed on the recording waveform for noise suppression, etc., the period is longer than the influence of the frequency component can be ignored. The average energy level over

  FIG. 1 is a diagram for explaining an example of the overall configuration of an information recording apparatus according to the present invention. The recorded user data 115 is managed by the controller 118, and is temporarily stored in the buffer 114 until a predetermined amount is reached. The recording data 127 sent out from the buffer 114 is converted into a recording code string 126 corresponding to the arrangement of marks (not shown) formed on the magneto-optical recording medium 117 in the encoder 113. The recording code string 126 is transmitted to the recording waveform generation circuit 112, where it is converted into a level generation signal 125 corresponding to the recording waveform. The encoder 113 and the recording waveform generation circuit 112 operate in synchronization with the reference time signal 128 generated by the reference time generator 119. The laser drive circuit 111 generates a laser drive current 124 with reference to the level generation signal 125, and causes the laser 110, which is a recording energy source, to emit light according to a predetermined recording waveform. The laser beam 123 emitted from the laser 110 is condensed on the magneto-optical recording medium 117 via the collimating lens 109, the half mirror 108, and the objective lens 116, and the recording film (not shown) is heated to mark it. Form. When reproducing information, the mark array on the magneto-optical recording medium 117 is scanned with a laser beam 123 having a level that is low enough not to destroy the mark. The reflected light from the magneto-optical recording medium 117 enters the polarization separation element 107 via the objective lens 116 and the half mirror 108. The polarized light separating element 107 separates the reflected light whose polarization plane is rotated in accordance with the magnetization direction of the mark into polarized light orthogonal to each other, and each is guided onto the photodetector 100 through the detection lens 106. The photodetector 100 converts the intensity of polarized light orthogonal to each other into an electrical signal proportional to them. The electric signal is amplified by a preamplifier 101 provided in each photodetector 100 and then transmitted to a differential amplifier 102. The differential amplifier 102 calculates a difference between input signals and generates a magneto-optical reproduction signal 120 corresponding to the presence or absence of a mark at a scanning position on the magneto-optical recording medium 117. The magneto-optical reproduction signal 120 is subjected to waveform equalization processing by the waveform equalizer 103, and further converted into a binary reproduction signal 121 by the binarizer 104. Further, the decoder 105 performs inverse transformation of the encoder 113 on the binarized reproduction signal 121 and stores the reproduction data 122 in the buffer 114. The reproduction data 122 in the buffer 114 is managed by the controller 118, and when it reaches a predetermined amount, it is output to the outside of the apparatus as user data 115 finally reproduced.

  FIG. 2 is a diagram for explaining in detail an example of the configuration of the recording processing system 129 in FIG. The recording data 127 is converted by the encoder 113 into a recording code string 126 that is information on the mark length, the space length, and the head position. The recording code string 126 is transmitted to the mark length classifier 201 and the recording waveform table 202. The mark length classifier 201 classifies the mark length of the recording code string 126 according to a predetermined rule, and inputs the classification result to the recording waveform table 202 as a mark length classification signal 204. On the other hand, the counter 200 refers to the recording code string 126, measures the time from the mark head position in units of the reference time signal 128, and generates a count signal 205. The recording waveform table transmits a level generation signal 125 reflecting a predetermined recording waveform to the laser driving circuit 111 in accordance with the recording code string 126, the mark length classification signal 204, and the count signal 205. The laser driving circuit 111 synthesizes a laser driving current 124 with reference to these level generation signals 125 and drives the laser 110 which is a recording energy source.

3 (a) to 3 (g) are diagrams for explaining an example of a recording code string mark and space and a recording waveform generating operation for recording the mark and space of the recording code string in the apparatus of the present invention and the apparatus of the present invention.
In the following explanation of the recording waveform, if the length or level of a part of the recording waveform is finely adjusted with reference to the recording patterns before and after for some reason, the recording waveform before the fine adjustment is made. Is a comparison. Therefore, the following description of the recording waveform is a comparison of the recording waveforms when the recording patterns are the same over a sufficiently long distance before and after the mark to be formed. Here, the sufficiently long distance means a distance sufficiently longer than the distance on the medium that is affected by the recording energy injection over a period of about the detection window width. FIG. 3A shows a reference time signal 128 serving as a time reference for the recording operation, and takes a cycle of Tw. FIG. 3B shows a recording code string 126 obtained as a result of converting the recording data by the encoder 113. Here, Tw is a detection window width and is the minimum unit of the change amount of the mark length and the space length in the recording code string 126. FIG. 3C shows an image of the mark arrangement on the recording medium. The laser beam spot for recording / reproduction scans in FIG. 3C from the left to the right. The mark 301 has a one-to-one correspondence with the “1” level in the recording code string 126 and is formed with a length proportional to the period. FIG. 3D shows a mark length classification signal 204 in the apparatus of the present invention. In this example, the mark length is classified into an odd multiple and an even multiple. FIG. 3E shows the count signal 205 in the present invention, which measures the time from the beginning of the mark 301 and the space 302 in units of Tw. 3 (f) and 3 (g) are examples of the recording waveform in the conventional invention apparatus and the invention apparatus corresponding to the recording code string 126 in FIG. 3 (b). These recording waveforms 303 and 304 are generated with reference to the count signal 205 and the recording code string 126. In the apparatus of the present invention, the mark length classification signal 204 is also referred to in addition to the above signals. The shortest period of the recording waveform pulse in the conventional invention apparatus is Tw, whereas in the apparatus of the present invention, it is 2 Tw, and the minimum cooling time in the example 304 of the recording waveform by the apparatus of the present invention is the example 303 of the recording waveform by the apparatus of the conventional invention. About twice as much.

Next, examples 400 to 406 of recording waveforms in the conventional apparatus will be described with reference to FIGS. As an example, it is assumed that the encoding rule by the encoder 113 is nRZI modulation after (1,7) code modulation. Therefore, the mark length and space length are always 2 Tw or more and 8 Tw or less. FIG. 4A shows the reference time signal 128, and each element of the recording processing system 129 operates according to this. FIG. 4B shows a count signal, which measures the time from the mark head in units of detection window width Tw. The timing at which the count signal shifts to 0 corresponds to the head of the mark or space.
FIG. 4C shows a recording waveform when a 2Tw long mark is formed, and the mark forming period 305 is composed of a pulse having a length of 1Tw and a level Pw1. The mark non-formation period is preceded by a period of 1 Tw width and level Pb, and then the Pa level is maintained until the next mark formation period. FIG. 4 (d) shows a recording waveform when a 3Tw long mark is formed, and the mark formation period 305 is a period of 0.5Tw and level Pa following the pulse of length 1Tw and level Pw1 as in FIG. 4 (c). , Length 0.5Tw, level Pw2 period. 4 (e) to (i) show the recording waveforms when 4Tw to 8Tw long marks are formed. Each mark length is 1Tw, the length is 0.5Tw, the level Pa period, the length 0.5Tw, and the level Pw2 period. It is added to the rear end of the mark forming part. Regardless of the space length, the mark non-formation period is preceded by a period of 1 Tw length and level Pb, and then the Pa level is maintained until the next mark formation period. In this recording waveform example, the shortest cooling period in the mark formation period 305 is 0.5 Tw.

Next, in order to explain the operation of the recording waveform generation circuit 112 in FIG. 2, examples 500 to 506 of recording waveforms in the apparatus of the present invention are shown using FIGS. 5 (a) to (i). The encoding rule of the encoder 113 is assumed to perform nRZI modulation after (1, 7) code modulation as in FIGS. 4 (a) to 4 (i). Therefore, the mark length and space length are always 2 Tw or more and 8 Tw or less. However, this does not limit the encoding rule of the encoder 113, and the present invention can be applied to the encoder 113 having an arbitrary encoding rule (for example, Eight-to-Fourteen Modulation, 8-16 modulation, etc.). It is. Further, the operation of the mark length classifier 201 in FIG. 2 is division by a divisor 2 (arithmetic operation), and the mark length classification signal indicates that the mark / space of the recording code string is an even multiple of the detection window width Tw. It shall be identified in the case of an odd multiple length. Although other divisors of 3 or more may be used as the divisor, the present invention shows a characteristic configuration when the divisor is 2. Further, although the operation of the mark length classifier 201 is a remainder calculation, this also does not particularly limit the structure and operation of the mark length classifier 201, and may be based on other classification methods. FIG. 5B shows a count signal 205 generated by the counter 200, which measures the time from the mark head in units of detection window width Tw. The timing at which the count signal shifts to 0 corresponds to the head of the mark or space. FIG. 5 (c) is a recording waveform at the time 2Tw length mark formation, mark forming period 305 is constituted by a length 1 Tw, the level Pw1 pulse. The mark non-formation period is preceded by a period of 1 Tw length and level Pb, and then the Pa level is maintained until the next mark formation period. FIG. 5 (e) shows a recording waveform when a 4Tw long mark is formed. The mark forming period 305 is the same as the pulse of length 1Tw and level Pw1 in FIG. 5 (c), followed by the length and length of 1Tw and level Pa. The period of 1Tw and level Pw3 continues. Thereafter, as shown in FIGS. 5 (g) and 5 (i), in the case of an even multiple-length mark of the detection window width Tw, a length of 1Tw, a level Pa period, a length 1Tw, and a level Pw3 period per 2Tw of mark length Is added to the rear end of the mark forming portion. FIG. 5 (d) shows a recording waveform when a 3Tw long mark is formed, and the mark forming period 305 is the same as the pulse of length 1Tw and level Pw1 as in FIG. 5 (c), followed by the period of length 1Tw and level Pw2. . Thereafter, as shown in FIGS. 5 (f) and 5 (h), in the case of an odd multiple-length mark of the detection window width Tw, the length is 1Tw per level 2Tw, the period of level Pa, the period of length 1Tw, and the level Pw3 Is added to the rear end of the mark forming portion. Regardless of the space length, the mark non-formation period is preceded by a period of 1 Tw length and level Pb, and then the Pa level is maintained until the next mark formation period. In this recording waveform example, the shortest cooling period in the mark formation period 305 is 1 Tw.

  The mark formation intermediate portion is a portion obtained by removing the mark formation leading end portion and the mark formation rear end portion from the mark formation period, and is a portion constituted by pulses having a constant period and a constant amplitude reflecting the mark length. The mark formation leading end portion is a portion before the mark formation intermediate portion within the mark formation period and is a portion corresponding to the mark formation leading portion. The mark formation rear end portion is a portion after the mark formation intermediate portion within the mark formation period, and is a portion corresponding to the mark formation end portion. The recording waveform is generally composed of a mark forming leading end portion, a mark forming intermediate portion, and a mark forming trailing end portion, but these three portions are not necessarily present.

  The recording waveform in the mark formation period 305 in the example shown in FIGS. 5C to 5I is composed of only the mark formation tip portion 507 and the mark formation intermediate portion 508. The interval between any two transition points of the energy level during the mark formation period for an arbitrary length mark is always longer than Tw and is an integral multiple of Tw. The mark formation leading end portion 507 is a portion having a level of Pw1 or Pw2, and the mark formation intermediate portion 508 is a portion in which the period of level Pw3, length 1Tw and the period of level Pa, length 1Tw are alternately continued. . The rear end portion of the mark formation has a length of zero and does not exist. In this case, the mark forming tip has a periodicity of 2 Tw with respect to the mark length. That is, when the mark length is 3Tw, 5Tw, and 7Tw (odd series), the recording waveform of the mark formation head portion 507 has a periodic similarity (length 1Tw, level Pw1, length 1Tw, level Pw2). When the mark length is 2Tw, 4Tw, 6Tw, and 8Tw (even number series), the recording waveform of the mark formation head portion 507 has a periodic similarity (length 1Tw, level Pw1).

  Next, other examples 600 to 606 of the recording waveform in the apparatus of the present invention will be described with reference to FIGS. Assume that the encoding rule of the encoder 113 is nRZI modulation after (1,7) code modulation, which is the same as in FIGS. 4 (a) to (i) and 5 (a) to (i). Further, the operation of the mark length classifier 201 in FIG. 2 is division by a divisor 2 (arithmetic operation), and the mark length classification signal indicates that the mark / space of the recording code string is an even multiple of the detection window width Tw. The case of odd multiple length shall be identified. FIG. 6B shows a count signal 205 generated by the counter 200, which measures the time from the mark head in units of detection window width Tw. The timing at which the count signal shifts to 0 corresponds to the head of the mark or space. FIG. 6C shows a recording waveform when a 2 Tw long mark is formed, and the mark forming period 305 is composed of a pulse having a length of 1 Tw and a level Pw1. The mark non-formation period is preceded by a period of 1 Tw length and level Pb, and then the Pa level is maintained until the next mark formation period. FIG. 6 (e) shows a recording waveform when a 4Tw long mark is formed. The mark forming period 305 is the same as the pulse of length 1Tw and level Pw1 as in FIG. 5 (c), followed by the length and length of 1Tw and level Pa. The period of 1Tw and level Pw3 continues. Thereafter, as shown in FIGS. 6 (g) and 6 (i), in the case of an even multiple-length mark of the detection window width Tw, a length of 1Tw per level 2Tw, a period of level Pa, a period of length 1Tw and level Pw3 Is added to the rear end of the mark forming portion. FIG. 5 (d) shows a recording waveform when a 3Tw long mark is formed, and the mark forming period 305 is the same as the pulse of length 1Tw and level Pw1 as in FIG. 5 (c), followed by the period of length 1Tw and level Pw2. . Thereafter, as shown in FIGS. 5 (f) and 5 (h), in the case of an odd multiple-length mark of the detection window width Tw, the length is 1Tw per level 2Tw, the period of level Pa, the period of length 1Tw, and the level Pw3 Is added to the end of the mark forming portion. Regardless of the space length, the mark non-formation period is preceded by a period of 1 Tw length and level Pb, and then the Pa level is maintained until the next mark formation period. In this recording waveform example, the shortest cooling period in the mark formation period 305 is 1 Tw.

The recording waveform in the mark formation period 305 in the example shown in FIG. 6 includes a mark formation leading end portion 507, a mark formation intermediate portion 508, and a mark formation rear end portion 607. The interval between any two transition points of the energy level during the mark formation period for an arbitrary length mark is always longer than Tw and is an integral multiple of Tw. The mark formation leading end portion 507 is a portion having a level of Pw1, and the mark formation intermediate portion 508 is a portion in which the period of level Pw3, length 1Tw and the period of level Pa, length 1Tw are alternately continued, after mark formation The end portion 607 is a portion having a level of Pw2. In this case, the mark formation front end portion 507 is always constant, whereas the mark formation rear end portion 607 has a periodicity of 2 Tw with respect to the mark length. That is, when the mark length is 3Tw, 5Tw, and 7Tw (odd series), the recording waveform of the recording waveform rear end portion 607 has a periodic similarity (length 1Tw, level Pw 2 ). When the mark length is 4Tw, 6Tw, or 8Tw ( even series), the recording waveform rear end portion 607 has periodic similarity (zero length).

The figure explaining the whole structure of the information recording device by this invention. The figure explaining the structure of the recording processing system in this invention. The figure explaining operation | movement of the recording processing system by this invention and a prior art. The figure explaining the example of the recording waveform of the recording processing system by a prior art. The figure explaining the example of the recording waveform of the recording processing system by this invention. The figure explaining the other example of the recording waveform of the recording processing system by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 ... Laser 111 ... Laser drive circuit 112 ... Recording waveform generation circuit 113 ... Encoder 115 ... User data 117 ... Magneto-optical recording medium 119 ... Reference time generator 120 ... Magneto-optical reproduction signal 122 ... Reproduction data 124 ... Laser drive current 125 ... Level generation signal 126 ... Recording code string 127 ... Recording data 128 ... Reference time signal 129 ... Recording processing system 200 ... Counter 201 ... Mark length classifier 202 ... Recording waveform table 204 ... Mark length classification signal 205 ... Count signal 305 ... Mark formation period 507 ... Mark formation leading end portion 508 ... Mark formation intermediate portion 607 ... Mark formation rear end portion.

Claims (1)

In an information recording apparatus that records information by injecting information into an edge by injecting a plurality of pulsed energy into a recording medium to form a recording mark,
Encoding means for converting information into a recording code string;
Classification means for classifying the mark length in the recording code string into an odd multiple and an even multiple with respect to the detection window width Tw;
Energy generating means for generating energy required for recording;
Each time the mark length in the recording code string increases by 2 Tw, the number of pulses of the injection energy within the mark formation period is increased by 1, and the classification result by the classification means is obtained by the odd multiple and the even multiple. Drive means for driving the energy generating means so as to have different recording waveforms according to
The different recording waveform is such that the shape of the recording waveform of the odd-numbered long mark formation head portion is different from the shape of the recording waveform of the even-numbered mark formation head portion,
On the other hand, the shape of the recording waveform of the mark forming head portion is raised from the first power level to the second power level and held and then lowered.
The shape of the recording waveform of the other mark formation head portion is raised from the first power level to the second power level and held, and then the third power between the first power level and the second power level is maintained. After falling to the level and holding it, it will fall further,
The period of the recording waveform of the other mark formation head part is the sum of the period held at the second power level and the period held at the third power level of the recording waveform of the one mark formation head part. An information recording apparatus characterized in that the information recording apparatus is longer than a period during which the second power level is maintained.

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