JPH10283637A - Information recording / reproducing apparatus and information recording / reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely form minute high density recording marks by irradiating the same region of a recording medium with plural light spots, preheating the recording region by a short wavelength light sport during a recording and forming the recording region employing a long wavelength light spot. SOLUTION: By a light spot 20, approximately same regions on a recording medium 30 are irradiated by two light spots having different spot diameters. The light spot having a smaller diameter preheats the medium 30 and becomes a first light spot 21 to support the recording and the erasing. The light spot with a larger diameter becomes a second light spot 22 to form recording marks. The first and the second spots 21 and 22, which irradiate the medium 30, are reflected by the medium 30, become parallel light beams by respective objective lenses, reflected by a prism and a wavelength separating filter and led to photodetectors through respective lenses.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an information recording / reproducing apparatus and an information recording / reproducing method for recording / reproducing information on / from a recording medium, and more particularly to a recording / reproducing apparatus and information recording / reproducing apparatus suitable for controlling a plurality of recording / reproducing means. It is about the method.

[0002]

2. Description of the Related Art A conventional apparatus is disclosed in, for example,
As described in JP-A-46039, a recording light spot is first arranged on a recording medium, and a reproduction light spot is arranged about 10 μm behind to make recording and reproduction independent. A recording / reproducing optical head capable of reproducing and monitoring recorded information has been realized.

[0003]

In order to increase the density, it is necessary to reduce the size of a mark having information and increase the amount of information per unit area. Further, it is important to perform recording and reproduction for forming a minute mark and reading the mark without malfunction. In order to control the length and width of the minute mark with high accuracy, it is necessary to reduce the light spot to be recorded, and to reduce the light spot, the wavelength of the light is shortened, and the numerical aperture of the lens that narrows the light is reduced. Need to be larger.

[0004] However, if the numerical aperture of the lens is too large, the light spot diameter becomes large due to the inclination of the recording medium or the like. Further, when the wavelength of the semiconductor laser is shortened, the energy density is increased, and both end faces forming the laser resonator are easily broken, and it is very difficult to increase the output. Also, since the transition energy increases,
It becomes difficult to drive the laser at a high frequency. Furthermore, even when the information on the conventional recording medium is used, when the light spot becomes smaller, the energy density of the light spot formed on the recording medium increases, the temperature of the recording medium rises, and existing information is destroyed. there is a possibility.

In the above-mentioned prior art, a processing system and method for converting a signal obtained from a recording / reproducing optical head into information, and formation of a minute recording mark accompanying high density have been described.
No consideration has been given, and there have been problems in reliability associated with the increase in the density of information, backward compatibility in which conventional information is effectively used, and the like.

SUMMARY OF THE INVENTION It is an object of the present invention to control a plurality of recording / reproducing means in the feasibility of an information recording / reproducing apparatus, and to form a minute recording mark with high density with high precision, thereby improving the reliability of information. Is to improve. It is another object of the present invention to perform backward compatibility by effectively using existing information by reproducing with a light spot corresponding to the recording density.

[0007]

In order to achieve the above object, the present invention provides a plurality of light sources comprising a long-wavelength laser capable of high output and a short-wavelength laser having a shorter wavelength and a smaller output than the laser wavelength. By irradiating the spot to almost the same area on the recording medium, and at the time of recording, pre-heating the area to be recorded with a short wavelength light spot and forming a recording area with a long wavelength light spot, the minute recording accompanying high density The mark is formed with high precision to improve the reliability of information. Also, in order to achieve the above-mentioned other object, when reproducing a high-density minute mark, a high-precision reproduction is performed with a small light spot by a short wavelength laser, and when reproducing conventional information, By reproducing using a large light spot by a long-wavelength laser, conventional information can be used effectively without destruction of information.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of the information recording / reproducing apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a short-wavelength laser (source of a short-wavelength laser; hereinafter, this is referred to as a laser 1); 2, a long-wavelength laser (a source of a long-wavelength laser; hereinafter, this is referred to as a laser 2); 3, 4 are photodetectors, 5 and 6 are laser drivers, 7 is a synthesizer, 8 is a recording pulse generation circuit, 11 is an input switch, 12 is a reproduction circuit, 13 is a PLL, 14 is a discrimination circuit, 15 is a controller, Reference numeral 20 denotes an optical head, 21 denotes a first light spot, 22 denotes a second light spot, and 30 denotes a recording medium.

An information recording / reproducing apparatus includes an optical head 20 including lasers 1, 2 and the like, and a recording medium 3 for recording information.
0, a recording processing system including a recording pulse generation circuit 8 and the like, and a reproduction processing system including a reproduction circuit 12 and the like for converting a reproduction signal obtained from the optical head 20 into information.

The recording medium 30 is composed of a recording film and a substrate for holding the recording film.
2 and a land 31 are provided. In the present embodiment, the recording mark is recorded on the land 31. Note that recording in the groove 32 is the same as recording in the land 31.

The optical head 20 irradiates substantially the same area on the recording medium 30 with two light spots having different spot diameters. The light spot having a small diameter is the first light spot 21 for preheating the recording medium 30 and supporting recording and erasing. The light spot having a large diameter is the second light spot 22 for forming a recording mark.

The laser light emitted from the laser 1 and the laser 2 is reflected from the recording medium 30, is received by the photodetectors 3 and 4, and is converted into an electric signal. The electric signals converted by the photodetectors 3 and 4 are input to preamplifiers 9 and 10 and input to terminals 11a and 11b of an input switch 11, respectively. The input switch 11 selects one of the terminals 11 a and 11 b according to a command from the controller 15 and outputs the signal to the reproduction circuit 12. The reproduction circuit 12 is composed of, for example, a circuit such as a waveform equalizer and a shaper, and a pulse signal from the reproduction circuit 12 is output from a PLL.
13 and a discrimination circuit 14. And the discrimination circuit 1
4 is input to the controller 15, and is converted into regular information.

The command and information data from the upper host are decoded by the controller 15 and the recording data are modulated, and are converted into a code string corresponding to the modulation method. The synthesizer 7 is an oscillator for generating a reference clock for the entire apparatus. As a technique for increasing the capacity, a ZC for changing the reference clock for each zone to keep the recording density on the inner and outer circumferences substantially constant.
When a recording method called AV (Zoned Constant Angular Velocity) is adopted, it is necessary to change the oscillation frequency of the synthesizer 7 according to the zone.

When recording information, the controller 1
5 and a reference clock from the synthesizer 7 enter a recording pulse generating circuit 8 to form a recording pulse train for controlling the length and width of a recording mark. Is converted.

These recording pulse trains are input to a laser driver 6, and the recording pulse is generated by a recording current from the laser driver 6.
The laser 2 is oscillated at a high output, and a recording mark corresponding to the code string is recorded by the second light spot 22 converged on the recording medium 30. At the same time, the laser driver 5 emits the laser 1 in response to a command from the controller 15 and preheats the recording medium 30 to a temperature near the recording or erasing temperature by the first light spot 21 converged on the recording medium 30. Thus, the recording mark formation is supported.

FIG. 2 shows a specific configuration example of the optical head 20 according to the present embodiment. The optical head 20 has a function of focusing light emitted from the laser 1 and the laser 2 on the recording medium 30. That is, as shown in FIG. 2, the laser 1 made of a semiconductor laser emits light, is converted into parallel light by a collimating lens 40, passes through a prism 41, is incident on an objective lens 42, and is placed on a recording medium 30. A light spot 21 is formed. The light reflected by the prism 41 is guided to a photodetector 51 by a lens 50. The output of the photodetector 51 is used as a signal for controlling the output of the laser 1. In addition, the laser 2 emits light, is converted into parallel light by the collimating lens 47, passes through the prism 46 and the wavelength separation filter 43, is reflected by the prism 41, and is then incident on the objective lens 42, and is incident on the recording medium 30.
A second light spot 22 is formed thereon. The light reflected by the prism 46 is guided to a photodetector 49 by a lens 48. The output of the photodetector 49 is used as a signal for controlling the output of the laser 2.

Then, the first light irradiated on the recording medium 30 is
The light spot 21 and the second light spot 22 are
Are reflected by the objective lens 42, become parallel light, and the reflected light of the first light spot 21 is reflected by the prism 41 and the wavelength separation filter 43, and is guided to the photodetector 4 by the lens 44. On the other hand, the reflected light of the second light spot 22 is reflected by the prism 41 and the wavelength separation filter 43
And is reflected by the prism 46 and guided to the photodetector 3 by the lens 45.

A servo for controlling the position of a light spot for recording and reproducing information includes a cylindrical lens (not shown) disposed in front of the photodetectors 3 and 4 and a photodetector (quadrant).
The focus error signal and the track error signal can be obtained by the steps 3 and 4. The error signal is input to the controller 15, and the servo signal (error signal and command signal) is sent to a servo circuit (not shown). To control the position of the light spot.

Next, an example of a recording method for recording on the recording medium 30 in the information recording / reproducing apparatus of the present invention will be described with reference to FIG. Here, the modulation method is (1, 7)
The case where the RLL code is adopted will be described. FIGS. 3A and 3B show recording code strings modulated according to the reference clock from the synthesizer 7 and the controller 15 and the regular information data described in FIG. This recording code string is 2Tw to 8T in the case of a (1,7) RLL code.
w, and the polarity is inverted by the modulation code “1” for mark length recording.
ro Inverse) signal. Here, Tw represents the detection window width, and is equal to the reference clock cycle Tw oscillated by the synthesizer 7.

The recording pulse generation circuit 8 generates a recording pulse train corresponding to the pulse portion of the recording code train. The recording pulse train shown in FIG. 3C differs from the first pulse in the length of the second and subsequent pulses, and the first pulse has a pulse width of 3/2 Tw with respect to the shortest pulse width 2 Tw.
Shorten it by Tw. The pulse widths after 3 Tw are obtained by adding the combination of the leading pulse 3/2 Tw, the second and subsequent pulse widths 1/2 Tw and the gap width 1/2 Tw (the same as the reference clock waveform). These pulses are generated in synchronization with a reference clock. Thereby, the accuracy of the pulse width and the pulse interval is improved. Further, the pulse width of the recording pulse train can be set to an arbitrary value which is an integral multiple of 1/2 Tw obtained from the reference clock.

FIG. 4 shows a recording waveform, a control signal, and a recording mark shape. FIG. 4A shows a recording waveform of the laser 1. Depending on the recording gate signal, so that the reproducing power level P _r1 of the laser 1 to the preheat level P _a, increasing the power level of the laser 1 by [Delta] P _a.

The recording waveform of the laser 2 shown in FIG. 4B is composed of a combination of a recording pulse train and a gap. At the trailing end of the recording pulse A or B, the recording pulse C causes an idle period of Tw width. Is provided. Recording pulse C
Is a certain time width (Tw width in the figure) from the last rear end of the recording pulse A or B (the last falling position of the mark forming portion).
Is provided so that heat from the last rear end of the recording pulse A or B does not change the temperature at the head rising position of the next pulse train.

The laser power of the laser 2 is set at four levels. That is, the reproduction power P _r2 during reproduction
When the erase power P _e by the recording pulse C, the recording pulse A, a recording power Pw _1, Pw ₂ by B.

With the recording waveforms of the lasers 1 and 2, it is possible to obtain a highly accurate recording mark shape shown in FIG. Here, the laser 1 can control the width of the recording mark while preheating for forming the recording mark, and the laser 2 can control the length of the recording mark. Further, by controlling a plurality of power levels, overwriting (overwriting) of information as described below can be performed.

As a technique for recording and reproducing information on a recording medium using a laser beam, an optical disk device and the like have already been put into practical use, and one technique of a rewritable optical disk device is as follows.
There is a phase-change type optical disk utilizing a reversible state change between a crystal and an amorphous. In order to obtain these two states, the recording medium is irradiated with high power (recording power), heated to a temperature equal to or higher than the melting point, and then rapidly cooled to an amorphous state. The recording medium is heated to a crystallization temperature by irradiating the recording medium with erasing power, and then gradually cooled to be in a crystalline state, so that overwriting can be performed by a single laser beam. Further, the present invention is also applicable to a light modulation overwrite method using a perpendicular recording medium.

In order to use the laser 1 and the laser 2 effectively, it is necessary to align the center positions of the spots in the circumferential direction and the radial direction. As an example of circumferential spot center alignment, a read signal amplitude obtained by fixing the recording power of lasers 1 and 2 to a certain value, changing only the spot center position, recording, and immediately after that, performing playback. Is the maximum or recording mark size (length and width)
Find the spot center position where is the largest. At this time, the spot center positions do not always coincide with each other, and will be described later (FIG. 1).
In general, the preheating spot slightly precedes, as in 0). Specifically, the laser 1 shown in FIG.
Alternatively, the laser 2 is moved in the circumferential direction of the recording medium 30, or the prism 41 is rotated in the circumferential direction of the recording medium 30. When the prism 41 is rotated, the emitted light from the laser 1 passes through the prism 41 and is hardly affected. However, since the emitted light from the laser 2 is reflected by the prism 41, the spot center position rotates the prism 41. It moves in the circumferential direction as compared with the case where it is not performed.

Although the means for moving the laser 1 or the laser 2 and the means for rotating the prism 41 are not shown in FIG. 2, any means capable of moving the laser 1 or the laser 2 can be used. Such a configuration may be used, and any configuration may be used as long as the prism 41 can be rotated.

In the radial alignment,
The positioning in the radial direction can be performed by well-known tracking control.

Next, a block diagram of a laser driver for driving each laser is shown in FIGS. FIG.
The laser driver 1 that generates the recording waveform of the laser 1
Here is an example. The recording gate signal shown in FIG. 4A is input directly and through an inverter to a current switch for high-speed driving, and the current amount of each current switch is set from the controller 15 through a D / A converter. . Each current amount is determined by the current of the laser 1 and the power characteristic (IL).
In the figure, it is indicated by the power (ΔP _a ) applied to the recording medium. ON / OFF of recording gate signal
4 flows through the laser 1 to obtain a recording waveform as shown in FIG. Further, the high frequency superimposing circuit is provided to reduce laser noise caused by the laser, and the high frequency superimposing may be suspended at the time of recording / erasing from the viewpoint of the life of the laser. Further, the APC circuit controls the output light level of the laser 1 based on the output signal of the photodetector 51 that directly receives the emitted light from the laser 1 shown in FIG.

FIG. 6 shows an example of a laser driver for generating a recording waveform of the laser 2. Each recording pulse (A, B, C) shown in FIG. 4B is input to each current switch for high-speed driving directly and through an inverter, and the amount of current of each current switch is sent from the controller 15 to the controller 15. Set through the D / A converter. Since each current amount depends on the current of the laser 2 and the power characteristics (IL characteristics), the powers (ΔPw ₁ , ΔPw) applied to the recording medium are shown in FIG.
₂ , ΔP _e ). When a current corresponding to the ON / OFF of each recording pulse flows through the laser 2, a current shown in FIG.
Is obtained.

In the recording waveforms and laser driving methods shown in FIGS. 4 to 6, the first light spot 21 having a small light spot diameter preheats the recording area, and the second light spot 22 having a large light spot diameter is recorded. It has been described that a region is formed. This is the case where it is difficult to increase the output and the high-frequency characteristics are not good as the characteristics of the short wavelength laser. Depending on the characteristics of the laser (when it is difficult to increase the output only), the second
The light spot 22 preheats the recording area, and the first light spot 2
A similar effect can be obtained even if 1 forms a recording area, and there is no problem at all.

FIG. 7 is a block diagram of an information recording / reproducing apparatus according to a second embodiment of the present invention.
Components equivalent to those of the first embodiment are denoted by the same reference numerals,
The explanation is omitted to avoid duplication.

The configuration of the present embodiment is obtained by adding a recording pulse generation circuit 16 to the configuration of the first embodiment of FIG. 1, and the basic operation of recording and reproduction is substantially the same as that described with reference to FIG. It is. However, it differs in that the laser 1 is driven at a somewhat higher frequency during recording.

FIG. 8 shows a recording waveform, a control signal, and a recording mark shape in this embodiment. FIG. 8 is substantially the same as FIG. 4 described above, except that only the recording waveform of the laser 1 is different. That is, in the present embodiment, the laser 1 is driven using a recording pulse D having a single frequency synchronized with the reference clock with respect to the recording gate signal used in FIG. The recording waveform of the laser 2 is the same as that shown in FIG. Even with such a combination, it is possible to obtain a recording mark shape substantially the same as that of FIG. As described above, even for a laser which is difficult to increase the output, it is possible to irradiate about twice the power by pulsating the laser rather than oscillating the laser steadily, and the range of setting the recording power in forming the recording mark is expanded. At the same time, it is possible to form a recording mark with high accuracy.

As for the spot position adjustment, the case where the spot position is physically adjusted by moving the laser 1 or the like or rotating the prism 41 has been described above, but FIG. 8A and FIG. By shifting the laser timing shown in B), the spot center position can be shifted. Specifically, optimal recording can be performed by adjusting the delay amounts of the laser drivers 5 and 6 for driving the laser 1 and the laser 2. As an example, as described with reference to FIG. 4, the power of each laser is fixed, and the delay amount of the laser driver 5 or 6 is changed.
By setting the delay amount at which the recording mark or the reproduction signal amplitude is maximized, optimal recording can be performed.

FIG. 9 is a diagram showing an arrangement of two light spots by the information recording / reproducing apparatus according to the third embodiment of the present invention. In FIGS. 1 and 7 (the first and second embodiments described above), the two light spots 21 and 22 are arranged substantially in the same area and in the same light spot 2.
It is assumed that the center positions of 1 and 22 substantially coincide. On the other hand, in the present embodiment shown in FIG. 9, the first light spot 21 is disposed in the direction opposite to the recording medium moving direction with respect to the center of the second light spot 22, and The center position interval is ΔL. Here, the first light spot 21 preheats the recording area, and the second light spot 22 forms the recording area. That is, the central position of the light spot for preheating the recording area is arranged so as to precede the central position of the light spot forming the recording area in the moving direction of the light spot.

As a result, a time lag such as a time required to elevate the temperature to a predetermined temperature by preheating and the consistency of superposition of heat by a plurality of light spots can be obtained, so that a highly accurate recording mark can be formed. Become.

FIG. 10 shows the result of calculating the temperature distribution of the recording medium during laser beam irradiation. The horizontal axis indicates the light spot movement distance, and the vertical axis indicates the radial direction of the recording medium. The traveling direction of the light moves from right to left, and the coordinates (0, 0) are the center position of the light spot. The calculation conditions are as follows: a perpendicular magnetization film used for magneto-optical recording is used as a recording medium, and the laser wavelength is 830.
nm, the numerical aperture (NA) of the lens was 0.6, the recording power was 6 mW, the linear velocity was 15 m / sec, and DC light irradiation with a constant power was used. This is the temperature distribution when the light spot moves from right to left in the figure and the center position of the light spot moves to the coordinates (0,0). The maximum temperature reached at this time is 242 ° C. From about 0.2μm
There is a maximum temperature position behind. Light spot diameter is λ / N
A can be approximated to about 1.4 μm, and the maximum temperature position is about １ ／ to ８ of λ / NA.

Therefore, the center distance ΔL between the light spots shown in FIG. 9 is at least λ / (7 × NA), where λ is the wavelength of the light spot for preheating the recording area.
By setting the value to λ / (8 × NA) or more, it is possible to absorb a time lag such as a time for raising the temperature to a predetermined temperature by preheating.

[0040]

As described above, according to the present invention, it is possible to form a minute mark with high density with high precision even in a laser in which it is difficult to increase the output, thereby improving the reliability of information. Further, there is an effect that backward compatibility that effectively uses conventional information can be easily performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an information recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical head in the information recording / reproducing apparatus according to the first embodiment of the present invention.

FIG. 3 is a waveform diagram for explaining an example of a recording method in the information recording / reproducing apparatus according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an example of a recording waveform, a control signal, and a recording mark shape in the information recording / reproducing apparatus according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a laser driver in the information recording / reproducing device according to the first embodiment of the present invention.

FIG. 6 is a block diagram of a laser driver in the information recording / reproducing device according to the first embodiment of the present invention.

FIG. 7 is a configuration diagram of an information recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of a recording waveform, a control signal, and a recording mark shape in an information recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 9 is an explanatory diagram showing an arrangement of two light spots in an information recording / reproducing apparatus according to a third embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a result of calculating a temperature distribution of a recording medium during laser beam irradiation.

[Explanation of symbols]

 1, 2 Laser 5, 6 Laser Driver 8 Recording Pulse Generation Circuit 11 Input Switch 21 First Light Spot 22 Second Light Spot 30 Recording Medium 31 Land 32 Groove

Claims (14)

[Claims] An information recording / reproducing apparatus for recording, reproducing, or erasing information by forming a recording area physically different from an unrecorded portion on a recording medium using a laser beam. An optical system for irradiating a plurality of light spots having different light spot diameters thereon, respective laser drivers for driving the plurality of light spots, a photodetector corresponding to each of the plurality of light spots, A reproduction system for reproducing a smaller number of electric signals than the electric signals obtained from the photodetector, wherein the plurality of light spots irradiate substantially the same area, and the area to be recorded by the small light spot is preheated to increase the size. An information recording / reproducing apparatus, wherein a recording area is formed by a light spot. 2. The laser driver according to claim 1, wherein the laser driver that drives the small light spot irradiates a constant recording power in a recording area, and the laser driver that drives the large light spot forms a recording area. An information recording / reproducing apparatus characterized in that a predetermined recording area is formed by changing a plurality of recording power levels at a high speed in order to achieve this. 3. The laser driver according to claim 2, wherein the laser driver for driving the small light spot changes recording power at a single frequency synchronized with or related to a reference clock for forming a recording area. An information recording / reproducing apparatus for preheating a recording area. 4. The reproduction system according to claim 1, wherein the reproduction system that reproduces a smaller number of electric signals than the electric signals obtained from the plurality of photodetectors has a lower recording density, and the electric system obtains from a larger light spot. An information recording / reproducing apparatus which reproduces using a signal and, when the recording density is high, reproduces using an electric signal obtained from a small light spot. 5. The information according to claim 1, wherein in order to form the plurality of light spots, laser lights having different wavelengths are used to form light spots having different sizes on a recording medium. Recording and playback device. 6. An information recording / reproducing apparatus for recording, reproducing or erasing information by forming a recording area physically different from an unrecorded portion on a recording medium by using a laser beam. An optical system for irradiating a plurality of light spots having different wavelengths thereon, respective laser drivers for driving the plurality of light spots, a photodetector corresponding to each of the plurality of light spots, and the plurality of photodetectors A reproduction system that reproduces a smaller number of electric signals than the electric signals obtained from the device, wherein the plurality of light spots have different center positions, and the short wavelength light spot precedes the long wavelength light spot; An information recording / reproducing apparatus characterized in that a recording area is pre-heated with a light spot having a wavelength and a recording area is formed with a light spot having a long wavelength. 7. The laser driver according to claim 6, wherein the laser driver that drives the short-wavelength light spot irradiates a constant recording power in a recording area and drives the long-wavelength light spot, An information recording / reproducing apparatus, wherein a predetermined recording area is formed by changing a plurality of recording power levels at high speed to form a recording area. 8. The laser driver according to claim 7, wherein the laser driver for driving the short-wavelength light spot has a recording power at a single frequency synchronized with or related to a reference clock for forming a recording area. To change
An information recording / reproducing apparatus characterized by preheating a recording area. 9. An information recording / reproducing apparatus for recording, reproducing or erasing information by forming a recording area physically different from an unrecorded portion on a recording medium using a laser beam. An optical system for irradiating a plurality of light spots having different wavelengths thereon, respective laser drivers for driving the plurality of light spots, a photodetector corresponding to each of the plurality of light spots, and the plurality of photodetectors A reproduction system for reproducing a smaller number of electric signals than the electric signals obtained from the device, wherein the plurality of light spots irradiate substantially the same area, or
The center position of multiple light spots is different, the short wavelength light spot precedes the long wavelength light spot, pre-heating the area to be recorded with the long wavelength light spot, and forming the recording area with the short wavelength light spot An information recording / reproducing apparatus characterized by the above-mentioned. 10. An information recording / reproducing apparatus for recording / reproducing information for recording / reproducing or erasing information by forming a recording area physically different from an unrecorded portion on a recording medium using a laser beam. During recording, a plurality of light spots having different light spot diameters irradiate substantially the same area on a recording medium to preheat a recording area with a small light spot and form a recording area with a large light spot. An information recording / reproducing method for reproducing only an electric signal obtained from a photodetector corresponding to one of the plurality of light spots during reproduction. 11. The recording medium according to claim 10, wherein at the time of recording, a plurality of light spots comprising a long wavelength laser and a short wavelength laser having a wavelength shorter than the laser wavelength are radiated to substantially the same area on the recording medium. An information recording / reproducing method, wherein a recording area is formed by a long-wavelength light spot while a recording area is preheated by the light spot. 12. The reproducing method according to claim 10, wherein at the time of reproduction, when the recording density is low, reproduction is performed using an electric signal obtained from a large light spot, and when the recording density is high, an electric signal obtained from a small light spot is reproduced. An information recording / reproducing method characterized in that the method is used for reproducing. 13. An information recording / reproducing apparatus for recording / reproducing or erasing information by forming a recording area physically different from an unrecorded portion on a recording medium using a laser beam. A recording method that uses a plurality of light spots including a long-wavelength laser and a short-wavelength laser having a shorter wavelength than the laser wavelength during recording, wherein the short-wavelength light spot precedes the long-wavelength light spot by a predetermined distance. In this way, the recording area is pre-heated with the short wavelength light spot, and the recording area is formed with the long wavelength light spot. At the time of reproduction, the recording area is obtained from the photo detector corresponding to one of the plurality of light spots. An information recording / reproducing method characterized in that only an electric signal to be reproduced is reproduced. 14. An information recording / reproducing apparatus for recording / reproducing or erasing information by forming a recording area physically different from an unrecorded portion on a recording medium using a laser beam. A method, wherein at the time of recording, using a plurality of light spots consisting of a long wavelength laser and a short wavelength laser shorter in wavelength than this laser wavelength, and irradiating a plurality of light spots to substantially the same area on the recording medium, Alternatively, the short wavelength light spot precedes the long wavelength light spot by a predetermined distance so that the area to be recorded with the short wavelength light spot is preheated, and the recording area is formed with the long wavelength light spot to reproduce the light. An information recording / reproducing method, characterized in that at times, only an electric signal obtained from a photodetector corresponding to one of the plurality of light spots is reproduced.