JP2688500B2 - Optical disk drive - Google Patents

Description

The present invention relates to an optical disc medium and an optical disc apparatus using the medium, for the purpose of enabling mark length recording on the optical disc, and an inner peripheral portion and / or an outer peripheral portion of the optical disc. The section is provided with a track for measuring sensitivity.

[Industrial applications]

The present invention relates to an optical disc medium and an optical disc device using the medium, and more particularly to an optical disc medium suitable for mark length recording / reproduction and an optical disc device.

Recording of binary data includes mark length recording and mark position recording. As shown in FIG. 5, the binary data is 101100.
The mark length means that 1 is a hole (mark), 0 is no hole, but is a mark position method, 1 is changed (start / end of hole), 0 is not changed. It is a record.

This (1) of FIG. 5 shows the binary data to be recorded (3)
Is recorded by mark position method (fabricated hole)
(2) shows the recording / reproducing signal, (5) shows recording by the mark length method (fabricated hole), and (4) shows the recording / reproducing signal. Data reading (decoding) from the reproduction signal is performed using (created from the clock read from the optical disk). In the mark position method, the pulse has 1 in the window, and in the mark length method, the window has 0. 1 if the state inside is different from the previous one,
It is 0 if it does not change.

Mark position recording is also called short hole recording, and mark recording is also called change point recording or long hole recording.

[Conventional technology]

Mark position recording is currently performed on an optical disc. The reason for this is that the size of the bits (holes) to be recorded in the optical disc varies depending on the medium sensitivity and the laser power, so that it is difficult to control the bit length and it is difficult to adopt the bit length method. That is, if the hole is large, the bit length (the length of the hole) extends forward and backward and becomes large, and the change point (zero cross point) shifts forward and backward, which may cause an error in decoding from the reproduced signal. With the mark position method, the presence or absence of a mark (hole) is a problem, and the presence or absence of an address changes depending on the size of the address, so that a read error does not occur.

In the magnetic disk, recording (magnet formation) is performed by sequentially applying a magnetic field in the opposite direction to the medium, and the bit length can be controlled regardless of the performance of the medium. Therefore, mark length recording is performed on the magnetic disk.

[Problems to be solved by the invention]

In mark position recording, information is 1 or 0 for one bit, but in mark length recording, there can be two pieces of information at the start point and end point of a bit respectively (recording density). However, it is difficult to record the mark length on the optical disc for the reason described above, and thus the recording density cannot be increased.

The present invention was devised to solve this problem, and an object thereof is to enable mark length recording even on an optical disc.

[Means for solving the problem]

 The present invention is configured as follows.

(1) In an optical disk device for recording information on an optical disk by generating a light beam according to the information to be recorded, a pulse width adjusting section for adjusting the pulse width, and data for the information recording area of the optical disk. At the time of writing, the writing is performed in an area different from the information recording area with the pulse width instructed by the pulse width adjusting unit, the reading error is detected to determine the optimum pulse width, and the pulse width adjusting unit An optical disk device comprising at least a control unit for setting the optimum pulse width.

(2) The control unit determines the optimum pulse width by detecting the read error in each pulse width by causing the pulse width adjusting unit to variously increase or decrease the pulse width for writing. 1) The optical disk device described above.

(3) The control unit determines a value within a range of a maximum pulse width and a minimum pulse width in a range where a reading error does not occur as the optimum pulse width, according to the above (1) or (2). Optical disk device.

(4) In an optical disc device that generates a light beam according to information to be recorded and records information on the optical disc, a power adjusting unit that adjusts the power of a light emitting element that generates the light beam, and the information of the optical disc. At the time of writing data to the recording area, the writing power is made to write in an area different from the information recording area with the recording power instructed by the power adjusting section, and the read error is detected to determine the optimum recording power,
An optical disc apparatus comprising at least a control unit for setting the optimum recording power in the power adjustment unit.

(5) The control unit determines the optimum recording power by detecting the reading error at each recording power by causing the power adjusting unit to variously increase and decrease the recording power to perform writing. 4) The optical disk device described above.

(6) The optical disk device according to (4) or (5) above, wherein the control unit determines the recording power when the reading error is the minimum as the optimum recording power.

(7) The another area is an area of an outer peripheral portion or an inner peripheral portion of the optical disk outside the information recording area, which is achieved by the optical disk device according to the above (1) or (4). .

As shown in FIG. 1, in the present invention, tracks T ₁ and T ₂ for sensitivity measurement are provided on the inner peripheral portion and / or outer peripheral portion of the optical disk 10.

When this optical disk is inserted into a recording / reproducing apparatus, the apparatus records on the track under various conditions, reproduces it, obtains an error rate, determines which recording condition is optimum for the disk, and performs the optimum recording. Recording will be performed later according to the conditions.

In FIG. 1, 12 is a head for recording / reproducing on / from the optical disk 10, 14 is a light emitting element driver for recording, 14a is a recording power changing circuit, and 16 is a pulse width varying circuit. Further, 20 is a microcomputer, and 22 is a reproduction amplifier for amplifying a reproduction signal of the optical disk.

[Action]

When the optical disc is inserted into the recording / reproducing device, the device
First, the sensitivity measurement track is recorded with various recording pulse widths (set in this way). An optical disk has tens of thousands of tracks, each of which is divided into 10 to 20 sectors, and a sensitivity measurement track is also divided into similar sectors, and a pulse having a different pulse width is recorded in each sector.

If the maximum recording frequency is 5MHz, the minimum pulse width is 100nS, which is its half cycle, and it is the maximum when recording with the 2by7 method (modulation method that converts 2 bits to 3 bits and 0 is not continuous 7 or more). The pulse width is 267nS. The maximum pulse width (longest bit) is recorded on the sensitivity measurement track, and if it is 267nS, it is within the range of ± 50ns or 2
Change from 17nS to 317nS in 5nS increments and change from 217 to S, 222nS, 2
A pulse with a width of 27nS, 317nS is recorded in each sector. That is, 217nS in the first sector, 222nS in the second sector, ...
A pulse with a pulse width of 317 nS is recorded in the sector. This recording is performed by the system of the computer 20, the pulse width variable circuit 16, the light emitting element driver 14, and the head 12.

After the above recording, reading is performed and the computer 20 checks the sector in which an error occurs. This reading is performed by the system of head 12, regenerative amplifier 22, and computer 20.

As the width of the recording pulse increases, the bits recorded on the medium also increase (the length of the hole increases). If the bit length on the medium is too small or too large, correct reproduction and demodulation cannot be performed and an error occurs. For example, an error occurs in that 7 pulses are written in one sector, but only 6 pulses can be read.

When checking the presence or absence of an error in each sector recorded by changing the recording pulse width, an error occurs in a sector with a small pulse width, an error does not occur at a certain pulse width when the pulse width becomes large, and an error occurs again when the pulse becomes larger. Will occur. Since it is considered that there is an optimum pulse width between the maximum pulse width and the minimum pulse width in the range in which no error occurs, the average value of these maximum / minimum pulse widths is the preferable recording pulse of the medium determined by the sensitivity. Width.

If the pulse width to be recorded is 267 nS as in this example, then 2
It seems that recording and reproducing with a pulse of 67 nS width is acceptable, but it is not suitable due to media sensitivity (recording power, ambient temperature, etc.), and recording with a pulse width wider or narrower than 267 nS. Will be optimal. Difference between the optimum pulse width obtained in the above test and the pulse width 267nS to be recorded Δ
W is stored (if the difference is only plus, the difference from the minimum value of 217 nS is ΔW), and this ΔW is used for actual recording.
To be added.

Since the variation of the width of the recorded pulse, that is, the length of the hole, only occurs before and after the hole, for example, when recording with a pulse having a width of 2 μm, a hole having a length of 2.1 μm is obtained, and thus, 3 μm
Recording with a pulse with a width of 3.1 μm results in a hole with a length of 3.1 μm.
Therefore, by adding the above-mentioned ΔW, it is possible to optimally record the pulses of all pulse widths (without causing an error).

By adopting this method, even if the sensitivity of the medium (optical disk) is different, it is possible to perform recording under the optimum recording conditions of each medium, and it is possible to perform mark length recording even on the optical disk.

The recording power may be adjusted instead of adjusting the pulse width. That is, writing is performed with various powers, an optimum power with few errors is obtained, and then recording is performed with that. The power changing circuit 26 performs this recording power adjustment / setting.

〔Example〕

FIG. 2 shows an embodiment of the present invention. As in all figures, the same parts as in the other figures have the same reference numerals.
Reference numeral 18 is an encoder that converts recording (writing) data output by the computer 20 into a pulse signal. Reference numeral 24 is a decoder for taking out recorded data from the output of the reproducing amplifier.

2 (b) is a diagram showing an example of the pulse width changing circuit of FIG. 2 (a), and FIG. 2 (c) is a diagram showing an example of the light emitting element driver 14 of FIG. 2 (a). The pulse width changing circuit 16 and the power changing circuit 26 constitute means for performing recording under optimum recording conditions.

In the pulse width variable circuit 16 of FIG. 2B, L _{1 to} Ln are delay lines, and S _{1 to} Sn are their selection switches. n = 20
Assuming that each delay line gives a delay of 5 nS, it is possible to increase the pulse width by 5 nS from 217 nS to 317 nS. That is, the input pulse IN is input directly or through the delay lines L ₁ , L ₂ , ... To the OR gate OR, and the output OUT of the OR gate is W + 5k (k = 0) with the pulse width of the input pulse being W (= 217nS). , 1,2, …… 20) It becomes nS.

Now, as a result of the test in the above manner, the optimum recording pulse width is determined, the pulse width ΔW to be added is determined, and when it is determined that the switch Si is closed, the microcomputer 20 stores the i, and Data for closing the switch Si is output when writing (normally writing data this time) on the optical disk. As a result, the switch Si is closed, and a pulse width of 5 iμS is added to the input pulse IN in this example.

The closing of the switch Si is a transistor switch S ₁ to Sn for example, to connect the base of each transistor to the output terminal of the flip-flop, by outputting the data to the computer 20 sets the corresponding flip-flops, easily performed It

In the light-emitting element driver 14 of FIG. 2 (c), D is the light emitting element (laser diode), Q ₃ is a transistor constituting a constant current source. Transistor Q ₃ keeps current flowing to light emitting device D
I ₁ is caused to flow to emit light, and the device is brought into a reading state. Q ₁ ,
Q ₂ is a pair of transistors that make up the current switch,
Q ₄ is a transistor forming a constant current source of the current switch. WA is a write amplifier, which turns on the transistor Q ₁ or Q ₂ according to the write signal WS.

Transistor Q ₂ is turned on, Q ₁ is in addition to the transistor Q ₄ supplies a constant current of the constant current I ₁ is a light-emitting element D when off
I ₂ also flows and generates strong light for writing (forming holes) on the optical disc. When the transistor Q ₁ is on and Q ₂ is off, the current I ₂ flows through Q ₁ and does not flow through the light emitting element D. Therefore, the current flowing through the light emitting element is only I ₁ , and writing (hole formation) is performed. I can't. In the reading mode instead of the writing mode, Q _{1 is} on and Q _{2 is} off, and only the constant current I ₁ flows in the light emitting element D.

When the power changing circuits 14a and 26 output the voltage ΔV to change the constant current I ₂ , the value of the current flowing through the light emitting element D at the time of writing changes, which in turn changes the writing power. Instead of obtaining the additional pulse width ΔW and optimally adjusting the recording pulse width with this, the current I ₂ may be corrected by obtaining the power ΔP to be added, and the power changing circuit 14a can obtain such power. Available for adjustment. The power changing circuit 14a can be composed of, for example, a voltage dividing resistor and a plurality of transistors for extracting the tap voltage. The control of these transistors can be performed in exactly the same way as in FIG. 2 (b).

FIG. 3 shows the relationship between the recording power and the recorded bit length of the two types of disks A and B. Recording pulse width is 2.5
However, if the recording power is low, recording is not performed (bit length 0), and if the recording power is high, the bit length is 2.5.
It becomes larger than μm. In addition, disk A is
The bit length is large even if the recording power is the same. That is, the disc A is more sensitive than the disc B. The graph of FIG. 3 was obtained by recording with a recording pulse width of 2.5 μm while changing the power, then reproducing, and estimating the bit length from the reproduced waveform.

When recording is performed with a constant recording pulse width, the difference in bit length is large, and this optical disk cannot be corrected by the same device without sensitivity correction. Furthermore, if there is a variation in recording power among devices, for example, a variation in recording power of ± 5% and a variation in medium sensitivity of ± 5%, the bit length changes by ± 10%, and the mark length changes. Recording is almost impossible.

FIG. 4 shows the results of carrying out the test of the present invention on these discs. The recording power is 7mW. For disk A, the error-free range is approximately -30 nS to +5 nS, and 0 is approximately -12 nS when the center of this range is optimal. In the disk B, the error-free range is about −10 nS to +25 nS, and ΔW is about +8 nS. Unit is 5
If nS, the former is -10nS and the latter is + 10nS. This makes it possible to perform optimum recording that is unlikely to cause an error.

〔The invention's effect〕

As described above, according to the present invention, the optimum pulse width or the recording power is obtained by recording on the optical disc, and the recording is performed by using the optimum pulse width or recording power. Therefore, the bit length recording can be performed on the optical disc and the recording density can be increased.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is a diagram showing an embodiment of the present invention, FIG. 3 is a graph showing the relationship between recording power and bit length, and FIG. 4 is a recording pulse width and number of errors. FIG. 5 is an explanatory diagram of mark length / mark position recording. In FIG. 1, reference numeral 10 is an optical disk, and T ₁ and T ₂ are tracks for measuring its sensitivity.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G11B 20/18 572 G11B 20/18 572F (72) Inventor Kazuo Nakajima Kamiodatanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Address 1015 within Fujitsu Limited (56) Reference JP-A-58-70438 (JP, A) JP-A-59-65952 (JP, A) JP-A-62-28935 (JP, A)

Claims (7)

(57) [Claims] 1. An optical disk device for generating a light beam according to information to be recorded to record information on an optical disk, and a pulse width adjusting section for adjusting a pulse width, and an information recording area of the optical disk. At the time of writing the data, the writing is performed in an area different from the information recording area with the pulse width instructed by the pulse width adjusting unit, the reading error is detected to determine the optimum pulse width, and the pulse width An optical disc device comprising at least a control unit for setting the optimum pulse width in an adjustment unit. 2. The control unit determines the optimum pulse width by detecting the reading error in each pulse width by causing the pulse width adjusting unit to increase / decrease the pulse width in various ways for writing. The optical disk device according to claim 1. 3. The optical disc according to claim 1, wherein the control unit determines a value within a range of a maximum pulse width and a minimum pulse width in a range where a reading error does not occur as the optimum pulse width. apparatus. 4. An optical disk device for generating information on an optical disk by generating a light beam according to information to be recorded, and a power adjusting section for adjusting the power of a light emitting element for generating the light beam, and the optical disk. When writing data to the information recording area, the writing power is made to write in an area different from the information recording area with the recording power instructed by the power adjusting section, and the read error is detected to determine the optimum recording power. An optical disc device comprising at least a control unit for setting the optimum recording power in the power adjustment unit. 5. The control unit determines the optimum recording power by detecting the read error at each recording power by causing the power adjusting unit to variously increase and decrease the recording power to perform writing. The optical disk device according to claim 4. 6. The optical disc apparatus according to claim 4, wherein the control unit determines the recording power when the read error is the minimum as the optimum recording power. 7. The optical disk device according to claim 1, wherein the other area is an area on the outer or inner circumference of the optical disk outside the information recording area.