JP2639841B2 - Recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus that performs recording on a recording medium such as a magneto-optical disk, a phase change disk, and a write-once optical disk.

2. Description of the Related Art There are various methods for recording data on a magneto-optical disk, which is one of recording media.
A weak magnetic field is applied to the recording layer of the magneto-optical disk formed by the perpendicular magnetic film, and a spot where data is to be written is irradiated with a light spot of a laser beam, and the temperature of the spot is raised to near the Curie point. As a result, data can be recorded on the magneto-optical disk in the form of a difference in the direction of magnetization at the location irradiated with the laser beam. Conventionally, a signal representing data to be recorded is directly supplied to a laser drive circuit.

However, when a signal representing data to be recorded (hereinafter referred to as an original signal) is directly supplied to a circuit for driving a laser to perform magneto-optical recording, as shown in FIG. Because of the influence, the deterioration of C / N increases and the recording density cannot be increased. In FIG. 6, P _9A is a laser
When the power is high, _P9B indicates the case where the laser power is low.

On the other hand, by reducing the width of the original signal as shown in FIG. 7 packed by a certain time, can be properly light spot P ₁₀ records compensates the effect of the irradiated heat-conducting at a high C / N In the case of signals having the same period, the recording density can be increased. However, the data to be recorded has changed,
When the wavelength of the original signal as shown in FIG. 8 has changed significantly, when recording pawl width of the original signal, the position of the light spot P ₁₁ of the laser beam recording data since etch deviates from the original signal correctly Can't play.

For this reason, a recording apparatus for a recording medium such as a magneto-optical disk, which can improve the recording density by increasing the C / N and can correctly reproduce the edge portion of the recording signal, has been desired.

Also, as shown in FIG. 9, when the original signal is directly supplied to a circuit for driving a laser to perform magneto-optical recording, the temperature of a portion on the magneto-optical disk where data is written rises to near the Curie point. take time. If the width of the original signal is long, the temperature of the location rises to a high temperature at the end of recording, and if the width of the original signal is short, the temperature of the location is lower than the temperature when the width is long. As described above, when the recording is performed based on the original signal, the temperature of the recording portion depends on the original signal, and therefore, the temperature of the portion to be recorded next differs depending on the width of the original signal. For this reason, it is not possible to appropriately control the temperature of the recording location.

Japanese Patent Application Laid-Open No. 62-8371 discloses a signal recording device that divides an irradiation pulse onto a disc into a pulse train in which a signal pulse of a recording signal is gradually reduced in a peak value and records a long signal pit. There has been disclosed a recording apparatus that suppresses a temperature rise on a disk surface due to continuous irradiation of laser light and prevents signal pits from expanding in a track width direction.

However, this is a configuration in which the heating value of the disk surface is adjusted by varying the irradiation intensity of the laser beam in accordance with the peak value of the pulse train in which the peak value gradually decreases, and the irradiation intensity of the laser beam is adjusted in accordance with the peak value. In order to change the pulse width, a driver circuit that changes the laser output linearly according to the input drive signal is required, and the optimum gradual decrease characteristic differs according to the number of pulses included in the pulse train, and a long signal pit is recorded. Since the peak value of the first pulse must be increased as in the case, the width of the leading edge of the signal pit becomes larger than the other signal pits, or vice versa, the more the pulse approaches the trailing edge of the signal pit. Of the signal pit, the width of the trailing edge of the signal pit is tapered, and the recording accuracy is likely to be reduced.

Also, JP-A-63-160017, "Recording device for optical disk"
Discloses a recording apparatus in which a laser beam is divided into a plurality of portions within a time corresponding to a bit length to be formed, and a pulse width of a leading pulse is larger than a pulse width of a subsequent pulse.

However, this method only divides a recording signal into a maximum of three, and when a period of a bit clock is T, a recording signal having a signal width of 3T to 5T cannot be divided into two parts. Irradiation, and for a recording signal with a signal width of 6T to 8T, it is divided into two, and the signal width is 9T
The recording signal of ~ 11T is divided into three parts. In each case, the laser light is radiated by the divided pulses having substantially the same width, so that the pit front edge part is formed and the pit body part subsequent thereto is formed. Therefore, it is difficult to control the temperature rise gradient of the disk surface, it is difficult to control the heat generation amount of the disk surface, and it is difficult to form a vertically long signal pit uniformly regardless of the pit length, It has problems such as causing jitter and S / N degradation.

Furthermore, Japanese Patent Application Laid-Open No. 63-263632 discloses an "optical disk recording apparatus" that divides a recording signal into two pulses, a front pulse and a rear pulse, within a time corresponding to the bit length to form a laser beam. By lowering the irradiation output of laser light immediately before the trailing edge, heat accumulation due to forward pulses is eliminated,
A recording apparatus has been disclosed in which the trailing edge of a recording signal is accurately defined by a rear pulse, jitter is suppressed, and S / N is improved.

However, this only divides the recording signal into two, and when the period of the bit clock is T,
Since the signal width of 3T, 4T and 5T recording signals cannot be divided into two parts, it is difficult to control the amount of heat generated on the disk surface by irradiating the laser beam, and for the recording signals with signal widths of 6T to 11T, Although the division into two is possible, the pulse width of the forward pulse increases as the signal width increases, and the width of the signal pits tends to increase accordingly, and there is a problem that the risk of interference with the signal pits of an adjacent track increases. Was something.

Also, JP-A-63-214922, "Semiconductor laser drive circuit"
Discloses a recording apparatus in which, for a recording signal exceeding a predetermined time width T, a portion exceeding the time width T is used as a high-frequency pulse to prevent a temperature rise of a recording medium at a trailing edge of the recording signal. However, in this case, it can be said that the leading edge of the recording signal coincides with the leading edge of the original signal, which prevents expansion of the recording pit due to a rise in temperature at the trailing edge of the recording signal. However, the interference between the preceding recording pit and the following recording pit tends to be a problem, and the laser beam irradiation power must be suppressed.
It had problems such as easy deterioration of the CN ratio.

The present invention has been made in view of the above-described conventional circumstances, and has as its object to provide a recording apparatus capable of restricting signal pits to a substantially constant width in the track width direction regardless of the length of a recording signal. Things.

Means for Solving the Problems In order to achieve the above object, the present invention provides a recording apparatus that forms a signal pit by irradiating a recording medium with a laser beam in a spot shape in accordance with a recording signal. A frequency converter for converting a clock signal having a large period, and an original signal in which signal pulses synchronized with the bit clock signal form a time series are supplied, and several periods of the clock signal starting from a leading edge of the original signal. Pit that lasts between the point in time when the first delay time corresponding to one minute elapses and the point in time when the second delay time elapses by adding several cycles, and causes a temperature rise above the Curie point of the recording medium. Pit leading edge forming pulse extracting means for extracting a leading edge forming pulse; and extracting the clock signal between a trailing edge of the pit leading edge forming pulse and a signal pulse trailing edge of the original signal. A pit body forming pulse extracting unit that forms a pit body forming pulse; and a pulse combining unit that combines an output of the pit leading edge forming pulse extracting unit and an output of the pit body forming pulse extracting unit and forms the recording signal. It is characterized by having.

Further, in the present invention, the pit leading edge forming pulse extracting means may include a first delay circuit for delaying the original signal by a first delay time, and a second delay circuit for delaying the original signal by a second delay time.
A delay circuit; and exclusive-OR means for obtaining an exclusive OR of an output of the first delay circuit and an output of the second delay circuit as the pulse for forming the leading edge of the pit; However, the present invention is characterized in that there is provided an AND means for calculating an AND of the output of the second delay circuit, the signal pulse, and the clock signal.

According to the present invention, the signal pulse synchronized with the bit clock signal is based on the time-series original signal, and when the first delay time has elapsed from the leading edge of the signal pulse and the second delay time has elapsed from the leading edge. Extracting a pit leading edge forming pulse that lasts for several cycles of the clock signal obtained by dividing the bit clock signal between the time when the delay time elapses and causes a temperature rise above the Curie point of the recording medium; A clock signal is extracted between the trailing edge of the pit leading edge forming pulse and the trailing edge of the signal pulse to form a pit body forming pulse, and the pit leading edge forming pulse and the pit body forming pulse are combined to form a recording signal. Regardless of the length of the pulse width of the original signal, the temperature of the magneto-optical disk surface after recording can be kept constant,
Since signal pits can be recorded with a substantially constant width in the track width direction, light spots applied to the magneto-optical disk surface do not interfere with adjacent light spots, improving jitter characteristics and eye patterns. In addition, the recording density can be improved.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 to FIG. FIG. 1 is a circuit diagram showing an embodiment in which the recording apparatus of the present invention is applied to a magneto-optical disk recording apparatus. FIG. 2 is a signal waveform diagram of each section of the circuit shown in FIG. FIGS. 4 and 5 show the relationship between the temperature rise of the magneto-optical disk surface recorded by the magneto-optical disk recording apparatus shown in FIG. 1 and the recording waveform, and FIGS. FIG. 9 is a circuit diagram showing a modification of the magnetic disk recording device.

In the magneto-optical disk recording device 1 shown in FIG. 1, an original signal (for example, an EFM modulated signal) modulated by data to be recorded on a magneto-optical disk is supplied to input terminals of a shift register 10 and an AND gate circuit 13, respectively. A bit clock signal synchronized with the original signal is supplied to the frequency conversion circuit 11. The frequency conversion circuit 11 converts the frequency of the input bit clock signal into a clock signal having a longer cycle. Hereinafter, the frequency-converted bit clock signal is simply referred to as a clock signal.

The original signal consists of a shift register 20 and an AND gate circuit.
It is provided to each of the 22 input terminals. Further, the clock signal is supplied to a clock input terminal of the shift register 20 and an input terminal of the AND gate circuit 22, respectively.
The shift register 20 outputs a first delay signal and a second delay signal, each of which is delayed by a predetermined time from the original signal in synchronization with the input clock signal. The first delay signal output from the shift register 20 is provided to the input terminal of the exclusive OR circuit 21. The second delay signal is applied to input terminals of an exclusive OR circuit 21 and an AND gate circuit 22, respectively.

The original signal, the second delay signal, and the clock signal applied to the input terminal of the AND gate circuit 22 are ANDed and output there. The signal output from the AND gate circuit 22 is a pit main body forming pulse indicated by a in FIG. 2 and forms the main part of the recording signal. The output signal of the AND gate circuit 22 is provided to the input terminal of the OR gate circuit 23 at the next stage. The exclusive OR circuit 21 calculates the exclusive OR of the first delay signal and the second delay signal, and outputs the result to the input terminal of the OR gate circuit 23 as a pit leading edge forming pulse indicated by the symbol b in FIG. give. The pit leading edge forming pulse also
Like the pit body forming pulse, it becomes a part of the recording signal.

The output signal (pit leading edge forming pulse) of the exclusive OR circuit 21 applied to the OR gate circuit 23 and the AND gate circuit
The output signal (pit body forming pulse) of 22 is synthesized by passing through an OR gate circuit 23 which is a pulse synthesizing means, and is output as a recording signal. The recording signal is supplied to input terminals of a polarity inversion circuit 24 and a differential amplifier 25, and the differential amplifier 25 performs differential amplification using the recording signal and the polarity inversion recording signal. The recording signal subjected to the differential amplification is applied to a laser driver (not shown), which drives the laser, irradiates a light spot corresponding to the recording signal onto the magneto-optical disk, and records on the recording surface of the magneto-optical disk. Then, a recording signal is performed as a recording pit.

When the phase of the recording signal is different from the phase of the clock signal, the phase of the recording signal corresponding to the portion indicated by the symbol “a” may be slightly different as shown in the lower part of FIG. It is about a clock pulse, and its influence on the pit formation accuracy can be ignored.

In the recording process by the magneto-optical disk recording device 1, the temperature on the magneto-optical disk surface follows the rise shown in FIG. First, the temperature of the magneto-optical disk surface rises to the Curie point in a short time by the pit leading edge forming pulse b included in the recording signal. After that, the temperature of the magneto-optical disk surface is kept constant by the pit body forming pulse a, that is, a pulse intermittent at the clock cycle. The pit body forming pulse a continues to be output until the fall of the original signal, but the temperature of the magneto-optical disk surface decreases with the end of the output.

Thus, for example, a pit leading edge forming pulse that lasts several clock cycles behind the leading edge of the original signal irradiates the recording medium with high power laser light without worrying about interference with preceding recording pits. The recording surface of the magneto-optical disk can be quickly raised to the Curie point, and once the recording surface of the magneto-optical disk is once raised to the Curie point, a pit body with a constant amplitude intermittently formed at the clock cycle is formed. Since the recording surface of the magneto-optical disk can be maintained at a substantially constant temperature by the pulse, it is possible to maintain the temperature of the recording surface of the magneto-optical disk constant after recording is completed, regardless of the pulse width of the original signal. Thus, signal pits can be recorded with a substantially constant width in the track width direction. Therefore, the light spot irradiated on the recording surface of the magneto-optical disk does not interfere with the adjacent light spots, so that the jitter characteristics and the eye pattern can be improved, and the recording density can be improved.

In the above embodiment, the exclusive OR circuit 21
For example, as in the case of the magneto-optical disk recording device 41 shown in FIG. 4, it can be configured by combining the polarity inversion circuit 26 and the AND gate circuit 27. In this example,
The first delay signal output from the shift register 20 is supplied directly to the AND gate circuit 27, the second delay signal is supplied to the AND gate circuit 27 via the polarity inversion circuit 26, and the AND gate circuit 22 Also supplied directly.

Also, like the magneto-optical disk recording device 51 shown in FIG. 5, the first delay signal output from the shift register 20 is supplied to the AND gate circuit 22, and the clock signal is output from the exclusive OR circuit 21. By supplying the signal to the OR gate circuit 29 together with the signal and providing the output signal of the OR gate circuit 29 to the AND gate circuit 22, the signal output from the AND gate circuit 22 may be used as a recording signal.

In the above embodiment, the case where the recording apparatus of the present invention is applied to a magneto-optical disk recording apparatus is taken as an example. However, the present invention can be applied to other recording apparatuses.

Effect of the Invention As described above, according to the present invention, a signal pulse synchronized with a bit clock signal is based on an original signal forming a time series, and starts from a leading edge of the signal pulse for several periods of the clock signal. Before the pit, which lasts between the point in time when the first delay time corresponding to the time elapses and the point in time when the second delay time elapses by adding several cycles, and causes a temperature rise exceeding the Curie point of the recording medium Along with extracting the edge forming pulse, a clock signal is extracted between the trailing edge of the pit leading edge forming pulse and the trailing edge of the signal pulse to form a pit body forming pulse. Are combined into a recording signal, so that a pit leading edge forming pulse that lasts for several clock cycles behind the leading edge of the original signal, without worrying about interference with the preceding recording pit, By irradiating the recording medium with a high-power laser beam, the recording surface of the magneto-optical disk can be quickly raised to the Curie point, and once the recording surface of the recording medium has been raised to the Curie point, the clock Since the recording surface of the recording medium can be maintained at a substantially constant temperature by the pit body forming pulse having a constant amplitude that is intermittent at intervals, the temperature of the magneto-optical disk surface after recording is completed regardless of the pulse width of the original signal. Can be kept constant, and signal pits can be recorded with a substantially constant width in the track width direction, so that light spots applied to the magneto-optical disk surface do not interfere with adjacent light spots. In addition, it has excellent effects such as improvement in jitter characteristics and eye pattern and improvement in recording density.

Further, according to the present invention, the pit leading edge forming pulse extracting means includes:
A first delay circuit that delays the original signal by a first delay time, a second delay circuit that delays the original signal by a second delay time, an output of the first delay circuit, and an output of the second delay circuit Exclusive-OR means for obtaining the pit leading edge forming pulse by exclusive-ORing the pit body forming pulse, wherein the pit body forming pulse extracting means includes an output of the second delay circuit, the signal pulse, and the bit clock signal. And the pit leading edge forming pulse and the pit main body forming pulse are formed accurately with a pulse width several times the clock pulse obtained by dividing the bit clock signal. This makes it possible to form an optimum recording signal in accordance with the temperature rise characteristics of the disk recording surface.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment in which the recording apparatus of the present invention is applied to a magneto-optical disk recording apparatus. FIG. 2 is a signal waveform diagram of each section of the circuit shown in FIG. 4 is a diagram showing the relationship between the temperature rise of the magneto-optical disk surface recorded by the magneto-optical disk recording device shown in FIG. 1 and the recording waveform, and FIGS. 4 and 5 are magneto-optical disks shown in FIG. 6 to 8 are diagrams showing various relationships between original signals and recording pits in a conventional magneto-optical disk recording device, and FIG. 9 is a diagram showing a conventional magneto-optical device. FIG. 4 is a diagram showing the relationship between the progress of the temperature rise on the magneto-optical disk surface recorded by the disk recording device and the original signal. 1,41,51… Magneto-optical disk recording device 11… Frequency conversion circuit 20… Shift register 21… Exclusive OR circuit 22… AND gate circuit 23, 29… OR gate circuit

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-8371 (JP, A) JP-A-63-160017 (JP, A) JP-A-63-263632 (JP, A) JP-A 63-263632 48617 (JP, A) JP-A-63-175230 (JP, A) JP-A-63-214922 (JP, A) JP-A-1-46231 (JP, A) JP-A-61-131258 (JP, A)

Claims (2)

(57) [Claims] 1. A recording apparatus for forming a signal pit by irradiating a recording medium with laser light in a spot form in accordance with a recording signal, wherein a frequency converter for converting a bit clock signal into a clock signal having a larger period, A time when an original signal in which signal pulses synchronized with the bit clock signal form a time series is supplied, and a first delay time corresponding to several cycles of the clock signal elapses from a leading edge of the original signal. And a pit leading edge forming pulse extraction for extracting a pit leading edge forming pulse that lasts between the time when a second delay time has been added by several cycles and that causes a temperature rise above the Curie point of the recording medium. Means for extracting the clock signal between the trailing edge of the pit leading edge forming pulse and the trailing edge of the signal pulse of the original signal, and forming the pit body forming pulse as a pit body forming pulse Extraction means, said pits before and combined with the output of the edge forming pulse extracting means and an output of said pit body forming pulse extracting means, a recording apparatus characterized by comprising a pulse synthesizing means to said recording signal. A first delay circuit for delaying the original signal by a first delay time; and a second delay circuit for delaying the original signal by a second delay time. And exclusive-OR means for taking the exclusive-OR of the output of the first delay circuit and the output of the second delay circuit as the pit leading edge forming pulse, and the pit body forming pulse extracting means comprises: 2. The recording apparatus according to claim 1, further comprising: an AND circuit that performs an AND operation on an output of a second delay circuit, the signal pulse, and the clock signal.