JP3226305B2 - Optical recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording apparatus for recording and erasing information on an optical recording medium by a photothermal method .

[0002]

2. Description of the Related Art In recent years, optical recording devices have become more reliable.
It is aimed at increasing the recording density. Hereinafter, an example of a conventional optical recording apparatus will be described with reference to the drawings.

FIG. 5 shows a configuration diagram of a conventional optical recording apparatus. In FIG. 5, reference numeral 10 denotes an optical recording medium,
Physical properties change when irradiated with heat energy. Numeral 20 denotes a laser emitting means for irradiating the optical recording medium 10 with a laser beam to supply the above-mentioned thermal energy. Numeral 30 denotes an erasing bias light controlling means for steadily emitting light from the laser emitting means 20 at the time of information recording. Numeral 40 denotes a recording pulse laser light control means for intermittently causing the laser light emission means 20 to emit light with a predetermined power at a timing synchronized with the rise of the input pulse signal Iw. 60 is a summing means is <br/> which causes superimposing the output signal of the recording pulse laser beam control means 40 to the output signal of the erase bias light control means 30.

The operation of the thus configured optical recording apparatus will be described below. FIG. 6 is a timing chart showing the operation of the conventional optical recording apparatus. First, the optical recording medium 1 on which information is recorded in this optical recording apparatus is shown.
0 will be briefly described. The optical recording medium 10 is generally called a phase change type, and a part of the recording film is melted by instantaneously irradiating a strong laser beam,
One bit of information is recorded by utilizing the fact that it changes from an initial crystalline state to an amorphous state when it solidifies again. When erasing this information, a medium level laser beam is irradiated to return to the crystalline state again. The apparatus shown in FIG. 5 is for overwriting information on the optical recording medium 10, that is, for recording new information while erasing old information.

FIG. 6 shows the output of the laser emitting means 20 in the apparatus shown in FIG. During the recording operation,
First, the erasing bias light control means 30 is operated by the laser light emitting means 2.
0 is made to emit light constantly with the power of Pe, and the recording area is crystallized. This corresponds to “0” in the binary recording information.
Further, the light emission power is intermittently increased to Pw in accordance with the rise of the input pulse signal Iw (transition from 0 to 1),
A part of the optical recording medium 10 is made amorphous. This corresponds to recording "1", and is executed by superimposing the output of the recording pulse laser light control means 40 on the output of the erase bias light control means 30. As a result, new information can be overwritten on old information. (For example, Optical Memory Symposium '90, p. 75)

[0006]

In the [0005] However, as described above arrangement moving, when erasing information with a steady power Pe, the recording material being formed on the optical recording medium along a recording track by thermal gradients gradually However, there is a problem that the material is degraded during repeated overwriting due to uneven stacking.

[0007] In view of the above problems, der those erase information while limiting movement of the material, so that to provide an optical recording apparatus capable of increasing the number of overwriting
You.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an optical recording apparatus according to the present invention uses a laser emission for irradiating a focused laser beam to an optical recording medium capable of recording and erasing information by a photothermal method. Means and group of binary signals to be recorded
And the recording signal string and the erasing signal sequence in synchronization with a clock signal from
A signal separating means for separating, depending on the transition of the erase signal sequence
From the amount of light that does not change the state of the optical recording medium,
Erasing laser pulse control means for causing the laser light emitting means to generate an erasing pulse laser beam having a light amount and pulse width suitable for erasing 1-bit information recorded on the recording medium ; Optical recording medium
Recording laser pulse control means for causing the laser light emitting means to generate a recording pulse laser beam having a light quantity and a pulse width suitable for recording 1-bit information on the optical recording medium from a light quantity which does not change the state. .

[0009]

According to the present invention, information is locally recorded and erased bit by bit with respect to the optical recording medium by the above-mentioned structure, so that the movement of the recording material, which has conventionally been a problem, is unlikely to occur. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical recording apparatus according to one embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an optical recording apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an optical recording medium, and reference numeral 2 denotes a laser light emitting unit. Reference numeral 3 denotes an erasing laser pulse control unit, and reference numeral 4 denotes a recording laser pulse control unit, which causes the laser emission unit 2 to emit light with a predetermined power and pulse width in accordance with the rise of the input signals Ie and Iw, respectively. Reference numeral 5 denotes a recording / erasing signal separating means, which outputs "0" from the input binary signal I, respectively.
In addition, "1" is separated into Iw in synchronization with the clock signal CLK. Reference numeral 6 denotes an adder which combines the outputs of the erase laser pulse controller 3 and the recording laser pulse controller 4 and causes the laser emitter 2 to emit a pulse during erasing and recording. Reference numeral 7 denotes a clock mark reading unit that changes the clock mark 1a formed on the optical recording medium 1 into an electric signal.
Reference numeral 8 denotes a synchronizing signal generating means for generating a clock signal CLK from the output of the clock mark reading means 7.

The operation of the thus configured optical recording apparatus will be described below with reference to FIGS.

FIG. 2 is a timing chart showing the timing of the clock signal and the laser emission in FIG. Clock mark reading means 7, a pulse signal CP which rises immediately after the optical recording medium 1 took read periodically formed clock marks 1a to a predetermined bit intervals
The synchronization signal generating means 8 generates a clock signal CLK by multiplying the pulse signal CP by a predetermined number. Thereafter, information recording / reproducing /
All erasures are executed in synchronization with the clock signal CLK. The recording / erasing signal separating means 5 includes a shift register 5a and mono-multis 5b and 5c. Shift register 5a is input at a timing synchronized with the clock signal CLK two
The value signal I is sent out one bit at a time,
b and 5c are shift registers when the clock signal rises.
When the output of the star 5a is "0" and "1", a pulse signal is generated. The erasing laser pulse control means 3 causes the laser light emitting means 2 to generate laser light having a light emission power Pe and a pulse width Te according to the output pulse of the monomulti 5b.

The recording laser pulse control means 4 is adapted to control the laser emission means 2 according to the output pulse of the mono-multi 5c.
Then, a laser beam having a light emission power Pw and a pulse width Tw is generated. Since the two light emitting states are superimposed on each other by the adding means 6, the laser light emitting means 2 is eventually turned into the state shown in FIG.
As shown in (1), when information corresponding to the input signals "0" and "1" is recorded, a laser is emitted at each power and pulse width.

Recording 1-bit information on the optical recording medium 1, that is, making the medium amorphous (recording "1" in this embodiment) is executed by a strong and short laser pulse as in the prior art. The difference from the conventional case is that the information is erased, that is, crystallized. In this embodiment, as described in the expression “0” is recorded, the medium is irradiated with a medium-power laser beam in a pulsed manner. This is to erase information locally. As described above, in the present embodiment, all recording and erasing of information are executed in synchronization with the clock signal CLK generated from the clock mark 1a formed on the optical recording medium 1 in advance.
As a result, it is possible to irradiate the erase laser pulse to the center position of the already recorded 1-bit information,
All information to be erased by the local erasing operation is erased.

The effect of this pulse erasure can be explained as follows. In the conventional example, in order to continuously emit a laser at the time of erasing, there is a problem that the material is moved and the overwriting characteristic is deteriorated as the number of times is increased. Even when erasing a bit, the laser must emit no light (or weakly emit light) between adjacent bits to which the erase pulse is applied.
(Po in FIG. 2) , the material is not heated during that time, and remains as it is. Therefore, the material is confined in the respective bit regions, and eventually no movement of the material occurs, and the number of overwrites is greatly improved. Note that during the recording or erasing pulse
When the light emission power Po is set to a weak light amount other than 0, FIG.
And how to emit a laser with that weak light
Although not particularly shown, for example, a conventional erase bias light
The same means as the control means 30 (FIG. 5) is used.
Set the amount of emitted light low enough so that the information is not erased.
In this case, the object can be easily achieved.

The relationship between the recording and erasing laser powers is Pw> Pe as in the prior art. Regarding the pulse width, Tw <T
e is more desirable. This is for the following reason. Amorphization in a phase change material occurs when the material is rapidly cooled from a high temperature to a low temperature, whereas crystallization occurs in the process of gradually cooling from a medium temperature to a low temperature. Therefore, it is better to irradiate a strong laser beam for an extremely short period of time when recording information, and to irradiate a medium laser beam for a period longer than during recording so that it does not cover adjacent bits (to prevent continuous light emission) when erasing. According to experiments by the inventors, it is desirable that 2 × Pe <Pw <3 × Pe 0.1 × Tc <Tw <0.2 × Tc 0.3 × Tc <Te <0.5 × Tc. Here, Tc is one clock cycle.

FIG. 3 and FIG.
This will be described with reference to FIG. In FIG. 3, the optical recording medium 1
Are divided into an area in which the synchronization mark 1a is formed and an information recording area 1b for recording information, and the information recording area does not have any unevenness such as a track groove.
The pulse recording / pulse erasing not only prevents the recording material from moving and unevenly distributed as described in the previous embodiment, but also prevents the track group from being moved.
With the effect of limiting the shape of the mark
Even if there is no, this forming a recording information mark of uniform shape
It becomes possible. For comparison, FIG. 4 shows a state in which information is overwritten on the optical recording medium 1 in this embodiment by a conventional method. In the conventional method, a part of the recorded information mark may be erased by the laser beam of the erasing bias power immediately after irradiating the optical recording medium 1 with the recording laser pulse. When this is reproduced, a sufficient signal amplitude is obtained. Although obtained was sometimes an error without erasing laser beam according to this embodiment is a pulse-like, yet always free calling
Since the light passes through the light (weak light emission) state, the preceding recording bit is not erased. In the present embodiment, although the optical recording medium 1 is a phase change type, the formation of uniform recording marks gutter
From the point of view, sufficient implementation effects can be expected without being limited to this . For example, a magneto-optical medium constituted by an RE-TM exchange-coupled multilayer medium as described in the Optical Memory Symposium '88 Transactions, p. 45 may be used. This medium performs inversion and non-inversion of magnetic domains in accordance with the irradiation laser power to record and erase information. Since switching between recording and erasing is performed by the binary value of the laser power, the same problem as that of the phase change type occurs. That is, a part of the preceding recording mark may be erased by the subsequent erasing operation. Therefore, such problems can be solved by using the present invention for this multilayer magneto-optical recording medium.

[0019]

As described above, according to the present invention, an appropriate light amount and pulse width are provided according to a binary input signal sequence.
Erase laser pulse to generate erase pulse laser light
By providing the control means and the recording laser pulse control means for generating the recording pulse laser light, information can be locally recorded and erased bit by bit on the optical recording medium.
By performing the removal , the movement of the recording material can be suppressed, and the shape of the recording information mark can be made uniform.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical recording apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining an operation in the embodiment.

FIG. 3 is an operation explanation for explaining an effect in the embodiment .
Figure

FIG. 4 is an operation explanation for explaining an effect in the embodiment .
Figure

FIG. 5 is a schematic diagram of a conventional optical recording apparatus.

FIG. 6 is a diagram illustrating the operation of a conventional optical recording apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical recording medium 2 Laser emission means 3 Erase laser pulse control means 4 Recording laser pulse control means 5 Recording / erasure signal separation means 8 Synchronization signal generation means

Continuation of front page (72) Inventor Takeo Ota 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-5-94620 (JP, A) .Cl. ⁷ , DB name) G11B ^7/ 00-7/125

Claims (5)

(57) [Claims] 1. A laser emitting means for irradiating a focused laser beam to an optical recording medium capable of recording and erasing information by a photothermal method, and synchronizing a binary signal group to be recorded with a clock signal. Signal separation means for separating the write signal sequence into a recording signal sequence and an erasure signal sequence, and the optical recording according to the transition of the erasure signal sequence.
Erasing laser pulse controlling means for causing the laser light emitting means to generate an erasing pulse laser beam having a light quantity and a pulse width appropriate for erasing 1-bit information recorded on the optical recording medium from a light quantity which does not change the state of the medium ; Changes the state of the optical recording medium according to the transition of the recording signal sequence.
Recording laser pulse control means for causing the laser light emitting means to generate a recording pulse laser beam having a light quantity and a pulse width suitable for recording 1-bit information on the optical recording medium from the light quantity not to be made. Optical recording device. 2. A and executes the erasing and recording of information by a crystalline state or amorphous state or different crystal states from high temperature state by irradiation of a laser beam to the optical recording medium produced by the process returning to the low temperature The optical recording device according to claim 1. 3. The method according to claim 1, wherein the instantaneous light quantity of the recording pulse laser light is larger than the instantaneous light quantity of the erasing pulse laser light , and the pulse width of the erasing pulse laser light is longer than the pulse width of the recording pulse laser light. The optical recording device as described in the above. 4. The optical recording apparatus according to claim 3, wherein the instantaneous light amount of the recording pulse laser beam is larger than twice and smaller than three times the instantaneous light amount of the erase pulse laser beam. 5. The pulse width of the recording pulse laser beam is longer than 1/10 of one clock cycle and shorter than 2/10 , and the pulse width of the erasing pulse laser beam is 3/3 of one clock cycle.
4. The optical recording apparatus according to claim 3, wherein the length is longer than / 10 and shorter than 5/10.