JP2002197661A - Optical disk recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust the timing of the sample hold in a short time for a reflected light receiving signal at the time of data recording operation, independently of the rotating speed of an optical disk. SOLUTION: The light receiving signal is binarized by a binarization circuit 402 and converted to a pulse signal, and the count of a reference clock is started from the rising edge of the binary pulse signal, and the sampling pulse is produced by counting up with a specified value, then the light receiving signal is subjected to sample-and-hold by a sample hold circuit 401 based on this sampling pulse. This sample hold output becomes a reflected light quantity detecting signal and does not depend on the rotating speed of the disk since the sampling pulse is produced from the light receiving signal in this case. Also, the sample timing is easily adjusted in a short time by setting the count up value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording apparatus capable of recording data on an optical disk for data recording by controlling the amount of laser light applied to the optical disk in accordance with recording data.

[0002]

2. Description of the Related Art As is well known, in an optical disc recording apparatus for recording data on a recording optical disc such as a CD-R / W, upon recording on an optical disc, light reflected from the disc is received and the amount of light is received. And various controls such as focusing, tracking, and laser power correction are performed based on the detection result. At this time, in order to improve the detection accuracy, a detection timing signal for detecting the amount of reflected light corresponding to the recording data is generated by the encoder circuit, and the delay is adjusted in accordance with the state of the apparatus.
At that timing, the sample and hold of the received light signal is performed.

[0003] By the way, the speed of disk rotation has been increased for the purpose of improving the recording speed, but with the increase in speed, it has become extremely difficult to adjust the timing of sample and hold. In particular, the timing of sample and hold is likely to be deviated due to fluctuations in external factors (such as temperature and power supply voltage), and high-precision detection cannot be performed. This means that increasing the recording speed is at its limit.

[0004]

As described above, in the conventional optical disk recording device, it is difficult to adjust the timing of the sample and hold with the increase in the rotation speed of the optical disk, and accurate detection cannot be performed. It has become difficult to increase the recording speed.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and makes it possible to easily and quickly adjust the sampling and holding timing of a reflected light reception signal during data recording regardless of the rotation speed of an optical disk. It is an object of the present invention to provide an optical disk recording apparatus capable of accurately detecting the amount of reflected light following an increase in the rotation speed of an optical disk and realizing a higher recording speed.

[0006]

In order to achieve the above object, an optical disk recording apparatus according to the present invention controls the light amount of a laser beam applied to a data recording optical disk in accordance with recording data. An apparatus for recording data by forming pits on an optical disc, wherein a sampling timing signal generating means for generating a sampling timing signal of the pit portion from a light receiving signal obtained by receiving reflected light from the optical disc; A reflected light amount detecting means for detecting a reflected light amount of the pit portion by sampling and holding a light receiving signal with the sampling timing signal, wherein the reflected light amount detecting level of the reflected light amount detecting means is constant. It is characterized in that the amount of light is controlled.

According to this configuration, the sampling timing is determined directly from the light receiving signal, not from the recording data, so that it is possible to easily follow the rotational speed of the disk.

In particular, the sampling timing signal generating means binarizes the light receiving signal and converts it into a pulse signal, and sets a sampling timing position after a lapse of a predetermined time from a rising edge or a falling edge of the pulse signal. Features.

According to this configuration, the unstable waveform portion disappearing within a predetermined time from the edge is not sampled, and the detection accuracy of the entire reflected light amount can be improved.

Further, the sampling timing signal generating means includes a counter for counting a reference clock, the reference clock is counted from the edge by the counter, and the sampling clock signal is output by counting up with a set value. And

According to this configuration, the timing adjustment of the sample and hold can be easily realized by changing the count-up value of the reference clock.

Further, the reflected light amount detecting means detects a bottom value of the light receiving signal, compares the bottom value with the sample / hold output, and outputs a difference signal as a reflected light amount detecting signal. And

According to this configuration, since the amount of reflected light is detected based on the bottom value, it is possible to accurately detect the difference from the total reflection level where no pit is formed.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of an embodiment of an optical disk recording apparatus according to the present invention. The optical disk 1 is rotated, for example, at a constant linear speed by drive control of the motor control circuit 4 for the disk motor 3. Recording and reproduction of information on the optical disk 1 are performed by the optical pickup 5. The optical pickup 5 is fixed to a drive coil 7 constituting a movable part of a linear motor 6, and the drive coil 7 is controlled by a linear motor control circuit 8.

The linear motor control circuit 8 includes a speed detection circuit 9
The speed signal of the optical pickup 5 detected by the speed detection circuit 9 is sent to the linear motor control circuit 8. A permanent magnet (not shown) is provided at a fixed portion of the linear motor 6. When the drive coil 7 is excited by the linear motor control circuit 8, the optical pickup 5 is moved in the radial direction of the optical disc 1.

The optical pickup 5 is provided with an objective lens 10 supported by a wire or a leaf spring (not shown). The objective lens 10 can be moved in the focusing direction (the direction of the optical axis of the lens) by driving the drive coil 11, and can be moved in the tracking direction (the direction orthogonal to the optical axis of the lens) by driving the drive coil 12. Is possible.

A laser beam is emitted from the semiconductor laser oscillator 19 by the drive control of the laser control circuit 13. The laser control circuit 13 includes a laser drive circuit 131
And a modulation circuit 132. The modulation circuit 132 takes in the recording data at the time of data recording, and generates a modulation pulse signal according to the value of the recording data. Laser drive circuit 131
Generates a laser drive signal during reproduction so that the amount of light received by the photodetector PD of the semiconductor laser oscillator 19 is constant, and outputs the signal to the semiconductor laser oscillator 19. At the time of recording, a laser drive signal is modulated and output by a modulation pulse signal from the modulation circuit 132. Laser power control at the time of recording is performed based on a detection result of a reflected light amount detection circuit 40 described later.

The light beam emitted from the semiconductor laser oscillator 19 is applied to a collimator lens 20 and a half prism 2.
1. The light is radiated onto the optical disk 1 via the objective lens 10. The reflected light from the optical disc 1 is guided to a photodetector 24 via an objective lens 10, a half prism 21, a condenser lens 22, and a cylindrical lens 23.

The photodetector 24 includes a four-divided photodetector cell 24.
a, 24b, 24c and 24d. The output signal of the photodetector cell 24a is supplied to one end of an adder 26a via a current / voltage conversion amplifier 25a. The output signal of the light detection cell 24b is supplied to one end of an adder 26b via an amplifier 25b. The output signal of the light detection cell 24c is supplied to the other end of the adder 26a via the amplifier 25c. The output signal of the light detection cell 24d is
It is supplied to the other end of the adder 26b via d.

Further, the output signal of the light detection cell 24a is:
The signal is supplied to one end of the adder 26c via the amplifier 25a. The output signal of the light detection cell 24b is supplied to one end of an adder 26d via an amplifier 25b. Photodetection cell 24
The output signal of c is supplied to the other end of the adder 26d via the amplifier 25c. The output signal of the light detection cell 24d is supplied to the other end of the adder 26c via the amplifier 25d.

The output signal of the adder 26a is a differential amplifier OP
2, and the output signal of the adder 26b is supplied to the non-inverting input terminal of the differential amplifier OP2. The differential amplifier OP2 outputs a signal related to the focus point according to the difference between the two output signals of the adders 26a and 26b.
This output is supplied to the focusing control circuit 27.
The output signal of the focusing control circuit 27 is supplied to the focusing drive coil 12. Thus, control is performed such that the laser beam is always just focused on the optical disc 1.

The output signal of the adder 26c is a differential amplifier OP
1, and the output signal of the adder 26d is supplied to the non-inverting input terminal of the differential amplifier OP1. The differential amplifier OP1 outputs a track difference signal according to the difference between the two output signals of the adders 26c and 26d. This output is supplied to the tracking control circuit 28. The tracking control circuit 28 creates a track drive signal according to the track difference signal from the differential amplifier OP1.

The track drive signal output from the tracking control circuit 28 is applied to the drive coil 1 in the tracking direction.
1 is supplied. Further, a track difference signal used in the tracking control circuit 28 is supplied to the linear motor control circuit 8.

By performing the focusing control and the tracking control, the sum signal of the output signals of the photodetector cells 24a to 24d of the photodetector 24, that is, the addition signal for adding both output signals of the adders 26c and 26d. The change in the reflectance from the bits formed on the tracks of the optical disc 1 corresponding to the recorded information is reflected in the output signal of the optical unit 26e. This signal is supplied to the data reproducing circuit 18. The data reproduction circuit 18 reproduces recorded data based on a reproduction clock signal from the PLL circuit 16.

When the objective lens 10 is moved by the tracking control circuit 28, the linear motor 6, that is, the optical pickup 5 is moved by the linear motor control circuit 8 so that the objective lens 10 is located near the center position in the optical pickup 5. Be moved.

The motor control circuit 4, the linear motor control circuit 8, the laser control circuit 15, the PLL circuit 16, the data reproduction circuit 18, the focusing control circuit 27, the tracking control circuit 28, the error correction circuit 32 and the like are connected via a bus 29. It is controlled by the CPU 30. The CPU 30 performs a predetermined operation according to a program recorded in the memory 2.

Further, the output signal of the adder 26e is supplied to a reflected light amount detection circuit 40, where the reflected light amount during data recording is detected. The detection result is supplied to the laser driving circuit 131, and the light emission amount of the laser is controlled so that the detection result becomes constant. This portion is a feature of the present invention.

FIG. 2 shows a specific configuration of the reflected light amount detecting circuit 40. The light receiving signal from the adder 26e is supplied to a sample / hold circuit 401, a binarizing circuit 402 and a bottom detecting circuit 403. . Bottom detection circuit 40
Numeral 3 is for detecting the lowest level value of the light receiving signal, and the detection result is supplied to the threshold value generating circuit 404. The threshold value generation circuit 404 generates a threshold value of a specified level based on the bottom detection value, and the generated threshold value is supplied to the binarization circuit 402.

The binarizing circuit 402 binarizes a light receiving signal based on a given threshold value and converts it into a pulse signal. The binarized pulse signal is supplied to a sampling pulse generating circuit 405. You. The sampling pulse generation circuit 405 includes a counter that counts a reference clock generated in the device, starts counting at a rising edge of an input pulse signal, and generates a sampling pulse by counting up with a predetermined value. Note that the counter is reset at the falling edge of the input pulse signal. This sampling pulse is supplied to the sample and hold circuit 401.

The sample-and-hold circuit 401 samples the received light signal at the timing of the sampling pulse.
The received light level value thus held is supplied to the comparison circuit 406 together with the bottom detection value obtained by the bottom detection circuit 403. The comparison circuit 406 calculates a difference value between the bottom detection value of the received light signal and the sample-and-hold value. The difference value is converted into a digital value by the A / D conversion circuit 407, and then the reflected light amount detection value It is supplied to the drive circuit 132. Laser drive circuit 1
32 is such that the reflected light amount detection value is constant at a specified value.
The laser power of the semiconductor laser oscillator 19 is controlled.

In the above configuration, the operation centering on the reflected light amount detection circuit 40 which is a feature of the present invention will be described below.

First, at the time of data recording, the modulation circuit 1
At 32, a modulated pulse signal based on the recording data is generated. At this time, the pulse width and pulse interval of the modulated pulse signal are set based on predetermined conditions in a range of 3T to 11T (T: reference clock cycle). Laser drive circuit 13
In 1, the laser drive signal is modulated and output by the modulated pulse signal. As a result, a light beam is output from the semiconductor laser oscillator 19 with a power corresponding to the value of the modulation pulse signal.

This light beam is applied to the optical disk 1, and
When the reflected light reaches the photodetector 24, photoelectric conversion is performed in each of the photodetection cells 24a to 24d, and a light reception signal is detected. Outputs of the cells 24a to 24d are converted into voltage signals by amplifiers 25a to 25d, respectively,
6c, 26d, and 26e add and combine. The light receiving signal thus obtained is supplied to the reflected light amount detecting circuit 40.

The operation of the reflected light amount detection circuit 40 will be described with reference to FIG.

FIG. 3A shows the light receiving signal (A) from the adder 26e. The bottom detection circuit 403 detects the lowest level value (bottom value (B)) of the light receiving signal (A). The threshold value generation circuit 404 generates a threshold value (C) of a specified level based on the bottom value (B). Binarization circuit 4
Numeral 02 binarizes the light receiving signal based on the given threshold value (C) and converts it into a pulse signal (D) as shown in FIG. Sampling pulse generation circuit 405
Detects the rising edge of the input pulse signal, starts counting the reference clock, counts up by a predetermined value,
A sampling pulse (E) as shown in FIG. 3 (c) is generated. By supplying this sampling pulse to the sample / hold circuit 401, a sample / hold signal (F) as shown in FIG.

Here, the waveform of the light receiving signal (A) becomes maximum at the start position of the pit formation by the light beam, and then gradually attenuates to a certain level. For this reason, it is desirable to set the sample and hold timing to a portion where the level is stabilized. Therefore, in the present embodiment, the sampling pulse generation circuit 405 counts the reference clock from the rising edge of the binarized pulse signal (D) and counts up by a predetermined value to generate a sampling pulse. The sampling pulse is set after a predetermined time has elapsed from the rise of the signal, that is, at a position where the received light signal is stabilized.

At this time, assuming that the count-up value is equivalent to 3T, pulses less than 3T are ignored. By doing so, a short pulse or an unnecessary noise component that does not provide a stable level value is not sampled and held, and the accuracy of detecting the amount of reflected light as a whole is improved. The count-up value is not limited to 3T, but may be set arbitrarily according to the disk rotation speed.

The sample / hold signal (F) is supplied to a comparison circuit 406 together with the bottom value (B) obtained by the bottom detection circuit 403, and a difference signal (G) shown in FIG. This difference signal (G) is converted into a digital value by the A / D conversion circuit 407, and then supplied to the laser drive circuit 132 as a reflected light amount detection value, and the semiconductor laser oscillator 19 is controlled so that the reflected light amount detection value becomes constant.
Is drive-controlled.

Therefore, according to the optical disk recording apparatus provided with the reflected light amount detecting circuit, the sampling pulse is directly generated from the received light signal instead of generating the sampling pulse from the recording data as in the related art. It is possible to easily follow the rotation speed of the disk. In particular, the sample and hold timing adjustment can be easily realized by changing the count-up value of the reference clock. Furthermore, since the amount of reflected light is detected based on the bottom value of the light receiving signal, it is possible to accurately detect the difference from the total reflection level where no pit is formed. This makes it possible to detect the amount of reflected light with high accuracy following the increase in the rotation speed of the optical disk, and to achieve a higher recording speed.

The present invention relates to a CD-R / W, DVD-R
/ W, DVD-RAM, MD, etc.

[0042]

As described above, according to the present invention, it is possible to easily and quickly adjust the sample and hold timing of the reflected light receiving signal during data recording, regardless of the rotation speed of the optical disk. As a result, it is possible to detect the amount of reflected light with high accuracy following the increase in the rotation speed of the optical disk, and it is possible to provide an optical disk recording device capable of realizing a higher recording speed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an optical disk recording device according to the present invention.

FIG. 2 is a block diagram showing a specific configuration of a reflected light amount detection circuit used in the embodiment.

FIG. 3 is a waveform chart for explaining the operation of the reflected light amount detection circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk 2 ... Memory 3 ... Disk motor 4 ... Motor control circuit 5 ... Optical pick-up 6 ... Linear motor 7 ... Drive coil 8 ... Linear motor control circuit 9 ... Speed detection circuit 10 ... Objective lens 11 ... Focus drive coil 12 ... Tracking Drive coil 13 ... Laser control circuit 131 ... Laser drive circuit 132 ... Modulation circuit 16 ... PLL circuit 18 ... Data reproduction circuit 19 ... Semiconductor laser oscillator PD ... Photodetector 20 ... Collimator lens 21 ... Half prism 22 ... Condenser lens 23 ... Cylindrical lens 24 photodetector 24a, 24b, 24c, 24d photodetection cell 25a, 25b, 25c, 25d current / voltage conversion amplifier 26a, 26b, 26c, 26d, 26e adder OP1, OP2 differential Amplifier 27: Focusing control circuit 2 ... Tracking control circuit 29 ... Bus 30 ... CPU 32 ... Error correction circuit 40 ... Reflection light quantity detection circuit 401 ... Sample hold circuit 402 ... Binary circuit 403 ... Bottom detection circuit 404 ... Threshold generation circuit 405 ... Sampling pulse generation Circuit 406: Comparison circuit 407: A / D conversion circuit

[Procedure amendment]

[Submission date] December 10, 2001 (2001.12.
10)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (4)

[Claims] 1. An optical disc recording apparatus for recording data by forming pits on an optical disc by controlling the amount of laser light applied to the data recording optical disc in accordance with recording data. Sampling timing signal generating means for generating a sampling timing signal of the pit portion from a light receiving signal obtained by receiving light; and detecting the amount of reflected light of the pit portion by sampling and holding the light receiving signal with the sampling timing signal. An optical disk recording apparatus, comprising: a reflected light amount detecting unit that controls the amount of the laser light so that the reflected light amount detection level of the reflected light amount detecting unit is constant. 2. The sampling timing signal generating means binarizes the light receiving signal and converts it into a pulse signal.
2. The optical disc recording apparatus according to claim 1, wherein a sampling timing position is set after a lapse of a predetermined time from a rising edge or a falling edge of the pulse signal. 3. The sampling timing signal generating means includes a counter for counting a reference clock. The counter counts the reference clock from the edge, counts up by a set value, and outputs a sampling timing signal. The optical disk recording device according to claim 2, wherein 4. The reflected light amount detecting means detects a bottom value of the received light signal, compares the bottom value with the sample / hold output, and outputs a difference signal as a reflected light amount detection signal. The optical disk recording device according to claim 1, wherein