JP2784965B2 - Optical disk recording / reproducing 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 disk recording / reproducing apparatus, and more particularly to an optical disk recording / reproducing apparatus for setting an optimum laser output when recording data on an optical disk.

[0002]

2. Description of the Related Art As an optical disk recording / reproducing apparatus capable of writing (recording) and reproducing information on / from an optical disk using a laser beam, for example, a write-once type (W
An optical disk recording / reproducing device O) is known. In such an optical disk recording / reproducing apparatus, the laser light is
The information is written in the form of a pit row by irradiating the optical disk with modulation by the FM signal. At the time of reproduction, information is reproduced by irradiating a laser beam onto the surface of the optical disc and converting reflected light from the pit row into a current.

[0003] Although the HL logic duty ratio of the EFM signal is 0.5, the length of the front and rear ends of the pits varies depending on the power of the laser beam, and asymmetry occurs. When reading information, the duty ratio of the read signal may not be 0.5 because the edge shape of the waveform changes depending on the performance of the optical pickup. For this reason, conventionally, a laser output calibration area is provided on an unrecorded optical disc, a recommended laser output for a predetermined wavelength is recorded in a lead-in portion of a blank disc, and the recommended laser output is recorded before recording on the optical disc. The reading is performed and the recording laser output is set.

[0004]

As described above, the conventional optical disk recording / reproducing apparatus records a recommended laser output on a lead-in portion of a blank disk, records the recommended laser output read at the time of recording, and records the laser output. Set to output. However, the shape of the pits recorded on the optical disk changes depending on each optical disk and the optical disk recording / reproducing device used, and the waveform shape of the read signal also changes with the optical pickup. There is a problem that an optimum laser output cannot be obtained for the apparatus.

It is an object of the present invention to provide an optical disk recording / reproducing apparatus capable of setting an optimum laser output for an optical disk used and an optical disk recording / reproducing apparatus.

[0006]

In order to solve the above-mentioned problems, an optical disk recording / reproducing apparatus according to the present invention provides an optical disk recording apparatus for recording information with several stages of laser outputs based on a recommended laser output recorded on a blank disk. An extracting circuit for extracting a 3T signal from the EFM signal, a peak-bottom-hold circuit for obtaining a peak value and a bottom value of an RF signal using a rising edge and a falling edge of the extracted 3T signal as reset pulses,
A setting circuit for selecting a laser output that minimizes the difference between the obtained peak value and bottom value from the laser outputs in the above several stages and setting the selected laser output as a recording laser output. Here, the high frequency compensation function operates with the non-operation set.

[0007]

According to the present invention, recording is performed with a laser output in several steps based on a recommended laser output recorded on a blank disk, and the recorded laser output information is read out, and the EFM is read.
The rising edge and the falling edge of the 3T signal obtained from the signal are used as reset pulses,
The laser output that minimizes the subtraction value of the two voltage signals obtained by holding is set as the optimum laser output.

[0008]

Next, the present invention will be described with reference to the drawings. At the time of recording on an optical disk, laser light emitted from a laser diode mounted on an optical pickup is focused on the optical disk rotated by a spindle motor. The current supplied to the optical pickup is modulated by a laser current modulator by an EFM signal generated by a CD encoder. During reproduction of the optical disk, a constant low current is supplied to the laser diode from the laser current modulator, and the emitted laser light is applied to the optical disk surface.
The reflected light reflected by the pit row of the optical disk is received by a photodiode of an optical pickup, converted into a voltage by an I / V converter, amplified by an RF amplifier, and thereafter subjected to a predetermined reproduction process.

FIG. 1 is a block diagram showing a main part of an embodiment of an optical disk recording / reproducing apparatus according to the present invention. As described above, the voltage signal converted by the I / V converter is amplified by the RF amplifier 1 and the DC component is removed by the capacitor 2, and then supplied to the delay circuit 3 and the comparator 10. The comparator 10 compares a DC component from a DC component detector 13, which will be described later, with the output of the capacitor 2, and sends the comparison result to the EFM demodulation circuit 11. The EFM demodulation circuit 11 performs EFM demodulation on the output of the comparator 10 and outputs the result to the low-pass filter 12 and the 3T detector 14. The low-pass filter 12 extracts a low-frequency component of the output of the EFM demodulator 11 and sends it to the DC level detector 13. The DC level detector 13 detects the DC level of the output of the low-pass filter 12 and supplies it to the comparator 10.

The 3T detector 14 detects only the 3T signal from the TTL level EFM signal from the EFM decoder 11, detects the rising edge of the peak hold circuit 4, outputs it as a reset pulse, and outputs the falling edge. And outputs it as a reset pulse of the bottom hold circuit 5. Peak / bottom hold circuit 4
And 5 are supplied with an RF signal whose DC component is removed by the capacitor 2 and time-adjusted by the delay circuit 3, and are peak-bottom-held by the rising edge pulse and the falling edge pulse from the 3T detector 14. . Here, the 3T signal is used because the RF signal is 3T
This is because the asymmetry of the 11T signal does not change so much and the duty ratio is almost 50%, whereas the 3T signal is easily affected by a slight change in the recording laser, and the detection sensitivity increases. Peak bottom
Outputs of the hold circuits 4 and 5 are supplied to a differential amplifier 6 via resistors R1 and R2. A resistor R3 is connected between the inverting input terminal of the differential amplifier 6 and the ground. The output of the differential amplifier 6 is added to 2.5 V by the adder 7 and supplied to the A / D converter 8. The addition of 2.5 V in the adder 7 is determined in consideration of the operating range (0 to 5 V) of the A / D converter 8. The digital signal obtained by the A / D converter 8 is a microcomputer (CP
In U) 9, predetermined reproduction signal processing is performed.

The operation of the embodiment shown in FIG. 1 will be described below. First, in the reproduction state, when the recommended laser output recorded in the lead-in area of the unrecorded optical disk is read, the microcomputer 9 sets the laser output in several steps around the recommended laser output. Thus, a predetermined frame in the optical disk calibration area is recorded with the set laser output. Next, the test area thus recorded is read. At this time, the normally set high-frequency compensation function operation is turned off.

As described above, the rising and falling edges of the TTL level EFM signal are used as reset pulses by the peak / bottom hold circuits 4 and 5, and only the 3T level bottom and peak values of the RF signal at that time are output. Then, the bottom value is subtracted from the peak value by the differential amplifier 6, and the one near zero has a pit-to-land ratio close to 1: 1. The voltage obtained by adding 2.5 V to the output of the differential amplifier 6 by the adder 7 is converted into a digital value by the A / D converter 8 and supplied to the microcomputer 9. The microcomputer 9 receives the digital signal supplied through the above processing, and determines and sets the laser output showing the value closest to 2.5 V as the optimum recording laser output. In the above embodiment, the reason why the EFM 3T signal is used as the reset pulse signal is that the EFM 3T signal is easily affected by a slight change in the recording laser, so that the detection sensitivity is improved.

[0013]

As described above, the optical disk recording / reproducing apparatus according to the present invention records the laser output in several steps based on the recommended laser output recorded on the blank disk, and outputs the recorded laser output information. Read, EF
The rising edge and falling edge of the M signal are detected, and the peak, bottom,
Since the laser output that minimizes the subtraction value of the two voltage signals obtained by holding is set as the optimum laser output, a very high-speed and accurate power setting is required for a short-time laser output setting in many steps. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of an optical disk recording / reproducing apparatus according to the present invention.

[Explanation of symbols]

1 RF amplifier 2 capacitor 3 delay circuit 4,5 peak
Bottom-hold circuit 6 Differential amplifier 7 Adder 8 A / D converter 9 Microcomputer 10 Comparator 11 EFM demodulator 12 Low-pass filter 13 DC level detector 14 3T detector 15 Rising edge detector 16 Falling edge detector

Claims (2)

(57) [Claims] 1. An optical disk recording / reproducing apparatus for recording information at several levels of laser output based on a recommended laser output recorded on a blank disk, comprising: an extraction circuit for extracting a 3T signal from an EFM signal; A peak-bottom hold circuit that obtains a peak value and a bottom value of an RF signal by using a rising edge and a falling edge of a reset pulse as a reset pulse; An optical disk recording / reproducing apparatus, comprising: a setting circuit that selects from a laser output and sets it as a recording laser output. 2. The optical disc recording / reproducing apparatus according to claim 1, wherein said optical disc recording / reproducing apparatus has a high-frequency compensating function, wherein said high-frequency compensating function is set to a non-operating state.