JPH06243498A - Optical disk device and its checking method/device - Google Patents

Abstract

PURPOSE:To provide an optical disk device which can be checked in a short period of time and with high accuracy. CONSTITUTION:In a check mode, a switch circuit 22 outputs the wobbling signal S26 received from a wobbling signal generator circuit 26 to a track driving circuit 20 and vibrates an objective lens 6. Thus an optical disk 28 is irradiated by the vibrating light beams and therefore the frequency of output signals of the photodiodes 4a and 4b are heightened by receiving the vibration influence and based on the output signal a tracking error signal S12 and an RF signal S14 having high frequency are generated and then outputted to a detection circuit 40 as the check signals S22. Thus the circuit 40 can perform the detection at a high speed by means of the check signal having high frequency and can check an optical disk device in a short period of time and with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc device capable of performing the inspection with high accuracy and in a short time, an inspection device for the optical disc device and an inspection method for the optical disc device.

[0002]

2. Description of the Related Art In a product inspection of an optical disk device or the like, for example, a tracking inspection for inspecting whether a light beam is irradiated on a track of the optical disk within a predetermined tracking error, and information of pits formed on the optical disk are used. R to check whether accurate RF (sum) signal can be obtained
An F signal test is performed.

The above-mentioned tracking inspection is carried out on the basis of a tracking error signal obtained from the output of a two-divided photodiode used for tracking servo by the three-spot method, for example, by rotationally driving the optical disk without applying tracking servo. The tracking servo based on the three-spot method uses three light beams: a main spot for reading a signal, and a leading side spot and a trailing side spot that are moved back and forth with respect to the main spot and shifted by half a track pitch on both sides of the main spot. A method that detects the amount of light reflected from the optical disc of the spot and trailing side spot with a photodiode, creates a tracking error signal indicating the output voltage according to the output difference between them, and performs tracking servo based on this tracking error signal. Is.

In the tracking inspection, since no tracking servo is applied, when the eccentric distance between the optical disc and the mounting axis of the optical disc is 80 μm, the optical disc is 1
During rotation, the light beam is 80 μm as shown in FIG.
In this range, the optical beam reciprocates in the radial direction of the optical disk, and the light beam is modulated between the pit rows. At this time, assuming that the number of revolutions of the optical disk is 600 rpm and the interval between the pit rows is 1.6 μm, the number of times n of modulation of the light beam generated in one revolution is as follows. n = 80 / 1.6 × 2 (round trip) = 100 (times) The number of times the light beam is modulated in one second from now on, that is, the frequency f of the tracking error signal is as follows. f = 100 × 600/60 = 1000 (Hz) = 1 (k
H)

FIG. 4A is a waveform diagram of a tracking error signal when the output voltage is plotted on the vertical axis and the time is plotted on the horizontal axis. The tracking error signal shown in FIG. 4A is output to the detection circuit, and the peak value is held in the detection circuit.
It is converted into a peak signal as shown in (B), and tracking inspection is performed using the voltage of this peak signal. The detection circuit has, for example, a storage element such as a capacitor, and when the absolute value of the voltage of the input signal exceeds the voltage corresponding to the terminal voltage of the storage element, further charge is stored in the storage element, and at other times. Is a circuit for generating a peak signal in which the charge is discharged from the storage element and the peak voltage of the input signal is held. Therefore, the peak signal output from the detection circuit is
The amplitude becomes a signal according to the frequency of the tracking error signal and the time constant of the detection circuit. Specifically, the lower the frequency of the tracking error signal and the smaller the time constant of the detection circuit, the larger the amplitude of the peak signal.

On the other hand, the RF signal inspection is performed, for example, on the basis of the RF signal generated from the output of the four-division photodiode used for the focus servo by the astigmatism method. Focus servo by the astigmatism method uses an optical component that generates astigmatism, and the position where the beam cross section of the astigmatic optical system becomes circular when the information recording surface of the optical disc is on the focal plane of the objective lens. In this method, a four-division photodiode is arranged, a focus error signal is created from four output signals of the four-division photodiode, and focus servo is performed based on the focus error signal. The RF signal is obtained as the sum signal of the four output signals of the four-division photodiode.

FIG. 4C is a waveform diagram of the RF signal. The RF signal shown in FIG. 4C is output to the detection circuit and converted into a peak signal as shown in FIG. 4D in which the peak value is held in the detection circuit, and R is converted using the voltage of the peak signal.
Perform F signal inspection.

[0008]

However, in the above-mentioned conventional method for inspecting an optical disk device, since the frequencies of the tracking error signal and the RF signal are as low as about 1 (kHz), the amount of charge leaked from the storage element of the detection circuit is low. Becomes larger and the peak signal output from the detection circuit is
As shown in (B) and (D), it has an amplitude that cannot be ignored. Therefore, tracking inspection and RF
In the signal inspection, when determining the voltage of the peak signal,
For example, it is necessary to take many sampling points in the peak signal and calculate the average value of the voltage of the peak signal at these points, the voltage of the peak signal cannot be detected at high speed, and the accuracy is low.

In order to solve this problem, simply increasing the time constant of the detection circuit and decreasing the amplitude of the peak signal takes time until the storage element reaches a steady state and obtains an effective peak signal. Time will increase.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide an optical disk device capable of performing the inspection in a short time and with high accuracy, an inspection device for the same, and an inspection method for the same.

[0011]

In order to solve the above-mentioned problems of the prior art and achieve the above-mentioned object, in the optical disk device of the present invention, the light beam is moved in the tracking direction based on the movement instruction. A light beam output means for irradiating the optical disc, and an optical disc that vibrates in the tracking direction at a predetermined cycle and a predetermined amplitude so that the detection signal operates at the time of inspection so that the frequency of the detection signal becomes a predetermined frequency. Vibration generating means for outputting a movement instruction indicating irradiation to the light beam output means is provided. Then, at the time of inspection, a light beam from the light beam output unit is vibrated and irradiated onto the optical disc according to a movement instruction from the vibration generation unit, thereby increasing the frequency of the detection signal of the reflected light beam, and in a short time. Enables highly accurate inspection. The vibration generating means may be provided in the inspection device instead of being provided in the optical disc device as described above.

The inspection apparatus of the present invention irradiates the optical disc with a light beam by moving it in the tracking direction by the light beam output means, detects the reflected light beam, and detects the reflected light beam of the optical disc based on the detection signal. An inspection device for inspecting an optical disk device for reproducing recorded information, wherein the light beam is vibrated in a tracking direction at a predetermined cycle and a predetermined amplitude on the optical disc so that the frequency of the detection signal becomes a predetermined frequency. It has a vibration generating means for outputting to the light beam output means of the optical disk device a movement instruction indicating that the irradiation is performed.

The detection signal is, for example, a tracking error signal or an RF signal.

In the inspection method of the present invention, an additional signal having a predetermined frequency and a predetermined amplitude is added to the tracking control signal, and the light beam from the light beam output means operated by the tracking signal added with the additional signal is added to the optical disc. The reflected light beam reflected by the optical disc is detected, an inspection signal corresponding to the peak voltage of the signal corresponding to the detection is generated, and the optical disc device is inspected based on the inspection signal.

[0015]

In the optical disk device of the present invention, during the inspection,
A vibration generation means outputs a movement instruction indicating that the optical beam is oscillated in the tracking direction with a predetermined period and a predetermined amplitude to be irradiated onto the optical disc, from the vibration generation means to the light beam output means. Then, based on the movement instruction, a light beam oscillated in the tracking direction at a predetermined period and a predetermined amplitude is irradiated onto the optical disc from the light beam output means.
Then, the reflected light beam from the optical disc is detected, and a detection signal corresponding to the detection is created. At this time, the detection signal is a signal obtained by adding a signal having a frequency corresponding to the vibration to a signal having a frequency corresponding to the rotation speed of the optical disc, and has a higher frequency than a signal having a frequency corresponding to the rotation speed of the optical disc. is doing. Then, the detection signal is output to, for example, an inspection device and inspected as an inspection signal by the inspection device to inspect the optical disc device.

In the inspection apparatus of the present invention, the vibration generating means irradiates the light beam output means of the optical disk device with the light beam vibrating the optical disk in a tracking direction at a predetermined cycle and a predetermined amplitude. The indicated movement instruction is output. When the light beam output means of the optical disk device inputs the movement instruction, it oscillates and irradiates the light beam on the optical disk in the tracking direction at a predetermined cycle and a predetermined amplitude. Then, the detection signal from the optical disc device is input to the inspection device, and the optical disc is inspected by using this detection signal as the inspection signal.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an optical disk device of this embodiment. The optical disk device 2 is a reproducing device that performs tracking servo by the three-beam method using the two-division photodiode 4a and focus servo by the astigmatism method using the four-division photodiode 4b.
It has a wobbling signal generation circuit 26 connected to the track drive circuit 20 by switching of No. 4 of FIG. Further, the optical disk device 2 has a reproduction mode for performing normal reproduction of the optical disk 28 and an inspection mode for performing product inspection.

As shown in FIG. 1, the optical disk device 2 includes
As the light beam detector 4, the objective lens 6, the focus coil 8, the track coil 10, the adder 12, the subtractor 14, the adder / subtractor 16, the focus drive circuit 18, the track drive circuit 20, the switching circuits 22 and 24, and the vibration generating means. Wobbling signal generation circuit 26, beam splitter 3
0 and a laser diode (LD) 32.

In the optical disk device 2, the light beam output from the LD 32 is transmitted through the beam splitter 30, condensed by the objective lens 6 and applied to the area of the optical disk 28 including a predetermined track. The light beam applied to the optical disc 28 is reflected by the optical disc 28, and the reflected light beam is reflected by the beam splitter 30 in the direction orthogonal to the incident angle and detected by the light beam detector 4.

The light beam detector 4 is composed of a four-division photodiode 4b, a leading photodiode (E) 4a and a trailing photodiode (F) 4a. The four-division photodiode 4b is placed in such a position that the light beam cross section of the astigmatic optical system becomes circular when the information recording surface of the optical disc 28 is on the focal plane of the objective lens 6. It is composed of C and D. Leading photodiode (E) 4a and trailing photodiode (F)
4a are arranged on both sides of the four-division photodiode 4b with a shift of about a half track pitch. The photodiodes A to F output electric signals of a level according to the amount of received light.

The adder 12 is a four-division photodiode 4
The output signal S4b corresponding to the amount of received light is input from b,
The RF signal S indicating the sum signal (A + B + C + D) of the output signals of the photodiodes A to D based on the output signal S4b.
12 is created and output to the switching circuit 22.

The subtractor 14 inputs an output signal S4a corresponding to the amount of received light from the preceding photodiode (E) 4a and the succeeding photodiode (F) 4a, respectively.
A tracking error signal S14 indicating a difference signal (EF) of these signals is created and output to the switching circuits 22 and 24.

The switching circuit 22 receives the RF signal S12 and the tracking error signal S14, and selectively outputs these signals to the detection circuit 40 in the inspection mode. The adder / subtractor 16 inputs the output signal S4b corresponding to the amount of received light from the four-division photodiode 4b, and based on the output signal S4b, the sum signal (A + D) of the output signals of the photodiodes A and D B, C
The sum signal (B + C) of the output signals of ((A +
D)-(B + C)) indicating a focus error signal S14
Is generated and is output to the switching circuits 22 and 24.

The focus drive circuit 18 includes an adder / subtractor 16
From the focus error signal S14, and the drive current S18 is generated based on the focus error signal S14.
Output to the focus coil 8. At this time, when the focus coil 8 receives the drive current S18, the focus coil 8 moves the objective lens 6 to an appropriate focus position according to the drive current.

The wobbling signal generation circuit 26 has a peak-to-peak voltage of about 0.2 (V) and a frequency of about 3, for example.
The wobbling signal S2 as a movement instruction of 0 (Hz)
6 is output to the switching circuit 24.

The switching circuit 24 inputs the tracking error signal S14 from the subtractor 14 and the wobbling signal S26 from the wobbling signal generating circuit 26, and outputs the tracking error signal S14 to the track driving circuit 20 in the reproducing mode. In the inspection mode, the wobbling signal S26 is output to the track drive circuit 20.

In the reproducing mode, the track driving circuit 20 receives the tracking error signal S24 from the switching circuit 24.
Is input, a drive current S20 is created based on the tracking error signal S24, and the drive current S20 is output to the track coil 10. At this time, the track coil 10 drives the drive current S2.
0 is input, and the objective lens 6 is moved according to the drive current so that the light beam is accurately applied to the track on which the optical disc 28 is being read.

On the other hand, in the inspection mode, the track drive circuit 20 receives the wobbling signal S2 from the switching circuit 24.
4 is input, and based on this signal S24, the drive current S20
Is generated and output to the track coil 10. At this time,
The track coil 10 receives the drive current S20, and causes the objective lens 6 to wobble (vibrate), for example, according to the drive current.

The operation of the optical disk device 2 will be described. The operation in the inspection mode will be described. In the inspection mode, the light beam is emitted across a plurality of tracks of the optical disc 28 according to the eccentric distance between the optical disc 28 and the disc mounting axis, as shown in FIG. However, since the objective lens 6 performs a wobbling operation, the objective lens 6 crosses the track while vibrating according to the vibration. In the inspection mode, the focus servo of the objective lens 6 is always performed.

The light beam output from the LD 32 passes through the beam splitter 30 and is irradiated onto the optical disc 28 via the objective lens 6. Then, the light beam is reflected by the optical disk 28, input to the beam splitter 30, reflected by the beam splitter 30, and output to the light beam detector 4 in the orthogonal direction. The light beam is received by the leading photodiode (E) 4a, the trailing photodiode (F) 4a, and the four-divided photodiode 4b of the light beam detector 4, and the leading photodiode (E) 4a and the trailing photodiode (F) are received. ) 4a outputs the output signal S4a to the subtractor 14 and the 4-division photodiode 4b outputs the output signal S
4b is output to the adder 12 and the adder / subtractor 16.

A focus error signal S16 is created by the adder / subtractor 16 based on the output signal S4b, and the focus servo of the objective lens 6 is performed via the focus drive circuit 18 and the focus coil 8 according to the focus error signal S16. Further, based on the wobbling signal S26 output from the wobbling signal generation circuit 26, the objective lens 6 is vibrated at a predetermined amplitude and frequency via the switching circuit 24, the track drive circuit 20 and the track coil 10.

As described above, based on the output signal S4a output from the preceding photodiode (E) 4a and the following photodiode (F) 4a while the focus servo is performed and the objective lens 6 is vibrated. hand,
The tracking error signal S14 is created by the subtractor 14 and output to the switching circuit 22. At this time, since the objective lens 6 is vibrating, the preceding photodiode (E) 4
a and the output signal S of the following photodiode (F) 4a
4a is a signal obtained by superimposing a signal generated according to the vibration on the output signal in a state where the objective lens 6 is not vibrated. Therefore, if the wobbling signal S26 is output so that the tracking error S14 is also affected by the vibration and a signal having an appropriate amplitude and frequency is superimposed, the tracking error signal S14 will be generated as shown in FIG. 3) having a frequency higher than the frequency of the tracking error signal shown in FIG.

Further, based on the output signal S4b output from the four-division photodiode 4b, the adder 12 performs RF
The signal S12 is created and output to the switching circuit 22. At this time, similarly to the tracking error signal S14 described above, the RF signal S12 is also affected by the vibration of the objective lens 6 and has a frequency higher than the frequency of the RF signal shown in FIG. The signal has a waveform as shown in (C). Then, the RF signal S12 and the tracking error S14 are selectively output to the detection circuit 40 by the detection circuit 40. As described above, since the optical disk device 2 causes the objective lens 6 to wobble (vibrate) in the inspection mode, the detection circuit 40 uses the tracking error S22 and the RF signal S22 having higher frequencies as inspection signals as compared with the case where the wobbling is not performed. Can be output to the detection circuit 40, which enables highly accurate and high-speed detection in the detection circuit 40 described later.

The reproduction mode will be described. Focus servo of the objective lens 6 by the four-division photodiode 4b, the adder / subtractor 16, the focus drive circuit 18, and the focus coil 8 is the same as in the inspection mode described above. In the reproduction mode, the tracking error signal S14 output from the subtractor 14 is selected by the switching circuit 24 and output to the track drive circuit 20. Then, based on the tracking error signal S14, the tracking servo of the objective lens 6 is performed via the track drive circuit 20 and the track coil 10.

The detection circuit 40 as the signal conversion means will be described. The detection circuit 40 is connected to the switching circuit 22 of the optical disk device 2 described above in the inspection mode, and the switching circuit 22 outputs the tracking error signal S22 or R.
The F signal S22 is input and the peak signal S40 is output.
FIG. 2 is a simplified circuit diagram of the detection circuit 40. Detection circuit 40
Is a circuit that holds the absolute value of the peak voltage of the input signal for a certain period of time. As shown in FIG. 2, the detection circuit 40 includes operational amplifiers 401, 404, 405 and diodes 402, 4
06, capacitors 403 and 407 as storage elements, and resistors 408 to 414.

For the positive input signal S22, the operational amplifier 401 operates, the voltage is accumulated in the capacitor 403, and the voltage corresponding to the accumulation appears at the junction point 420. Also,
The operational amplifier 405 operates for the negative input signal S22, and the inverted voltage is stored in the capacitor 407.
A voltage corresponding to the accumulation appears at the junction point 420. Further, the operational amplifier 404 amplifies the signal at the junction point 420 and outputs it as a peak signal S40.

In FIG. 3B, the detection circuit 40 is provided with the tracking error signal S2 shown in FIG.
The waveform diagram of the peak signal S40 output when 2 is input is shown. 3D is a waveform diagram of the peak signal S40 output when the detection circuit 40 receives the RF signal S22 shown in FIG. 3C from the switching circuit 22. Figure 3
As shown in FIGS. 4A and 4C, the tracking error signal S22 and the RF signal S22 output from the optical disk device 2 are affected by the wobbling operation of the objective lens 6 and are shown in FIGS. The signal has a higher frequency than that of the conventional optical disk device shown in FIG. Therefore, the peak signal S40 of the detection circuit 40 for the tracking error signal S22 and the RF signal S22 is as shown in FIG.
As shown in (D), both become signals close to a DC signal, the voltage of the peak signal S40 can be detected (detected) with high accuracy and at high speed, and the inspection time of the optical disk device 2 can be shortened. it can.

As described above, the optical disc apparatus 2 of the present embodiment, in the inspection mode, uses the wobbling signal S26 from the built-in wobbling signal generating circuit 26 to vibrate the objective lens 6 while tracking the tracking error signal. And RF signal. Therefore, the tracking error signal and the RF signal having high frequencies can be output to the detection circuit 40, and the voltage of the peak signal created by the detection circuit 40 can be detected at high speed without degrading the detection accuracy. The inspection 2 can be performed at high speed and with high accuracy.

The invention is not limited to the embodiments described above,
For example, the wobbling signal generation circuit 26 and the switching circuits 22 and 24 may not be built in the optical disk device 2 but may be externally attached to the optical disk device 2 at the time of inspection. Further, an inspection device having the wobbling signal generation circuit 26 and the detection circuit 40 may be connected to the optical disc device 2 to perform the inspection. Also,
The optical disk device 2 may be configured to perform the tracking servo not by the three-spot method as described above but by another push-pull method or the like. Further, the optical disc apparatus 2 may be configured such that the focus servo is performed not by the astigmatism method as described above but by another knife edge method or the like. Further, the optical disk device 2 may output signals other than the above-described RF signal and tracking error signal to the detection circuit 40 as inspection signals. Further, the present invention can be used not only in the optical disk device but also in other magneto-optical disk devices that perform tracking servo.

[0040]

According to the optical disk device, the inspection device and the inspection method thereof of the present invention, the frequency of the detection signal from the optical disk device can be increased at the time of the inspection of the optical disk device, and the detection having this high frequency can be performed. The signal can be used to perform inspection of the optical disk device with high accuracy and in a short time. According to the optical disc device of the present invention,
Since the optical disk device has the vibration generating means, it is not necessary to apply a movement signal from the outside to the light beam output means when the optical disk device is inspected, and the inspection can be performed easily even after factory shipment. it can. Further, according to the inspection device of the present invention, since the inspection device has the vibration generating means, it is not necessary to provide the optical disk device with the vibration generating means, and the cost of the optical disk device can be reduced.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram of a detection circuit according to an embodiment of the present invention.

3A and 3B are waveform diagrams of a tracking error signal and an RF signal created by the optical disk device of this embodiment, and FIGS. 3C and 3D are output by a detection circuit. It is a wave form diagram of a peak signal about the signal shown to and (B).

4A and 4B are a tracking error signal and an RF generated by a conventional optical disk device, respectively.
Signal waveform diagrams (C) and (D) are peak signal waveform diagrams of the signals (A) and (B) output from the detection circuit.

FIG. 5 is a diagram for explaining a path of a light beam on an optical disc in an inspection mode of the optical disc device.

[Explanation of symbols]

2 ... Optical disk device 4 ... Light beam detection unit 4 4a ... Leading photodiode (E), trailing photodiode (F) 4b ... 4-division photodiode 6 ... Objective lens 8. ..Focus coil 10 ... track coil 12 ... adder 14 ... subtractor 16 ... adder / subtractor 18 ... focus drive circuit 20 ... track drive circuit 22, 24 ... switching circuit 26 ... Wobbling signal generation circuit 28 ... Optical disk 30 ... Beam splitter 32 ... LD 40 ... Detection circuit 401,404,405 ... Operational amplifier 402,406 ... Diode 403,407 ... Capacitors 408 to 414 ... Resistance

Claims (5)

[Claims] 1. An optical disk device for irradiating an optical disk with a light beam, detecting a reflected light beam of the optical disk, and reproducing recorded information of the optical disk based on a detection signal corresponding to the detection. A light beam output means for moving the beam in the tracking direction to irradiate the optical disc, and a light beam output means for operating the optical disc on the optical disc at a predetermined period and at a predetermined frequency so that the detection signal operates at a predetermined frequency. And a vibration generating means for outputting to the light beam output means a movement instruction indicating that irradiation is performed by oscillating in the tracking direction with the amplitude of, and at the time of inspection, the light beam output means moves from the vibration generating means. The optical disc is irradiated with the light beam according to an instruction, and a detection signal of the reflected light beam is used as an inspection signal. Disk apparatus. 2. An optical disk is irradiated with a light beam by moving it in the tracking direction by a light beam output means, the reflected light beam is detected, and the record information of the optical disk is reproduced based on a detection signal corresponding to the detection. An inspection device for inspecting an optical disc device, comprising irradiating the optical disc by vibrating a light beam in a tracking direction at a predetermined period and a predetermined amplitude so that the frequency of the detection signal becomes a predetermined frequency. Vibration generating means for outputting the indicated movement instruction to the light beam output means of the optical disk device, and signal conversion means for converting the detection signal from the optical disk device into a peak signal corresponding to the peak voltage of the detection signal. At the time of inspection, the vibration generation means outputs the movement instruction to the optical disc device, and a detection signal from the optical disc device. Inspection apparatus for an inspection signal peak signal converted by the signal converting means. 3. The optical disk device according to claim 1, wherein the detection signal is a tracking error signal. 4. The detection signal is an RF signal.
The optical disk device described. 5. A tracking control signal is added with an additional signal having a predetermined frequency and a predetermined amplitude, and a light beam from a light beam output means operated by the tracking signal added with the additional signal is applied to an optical disk, An inspection method of detecting a reflected light beam reflected by an optical disk, creating an inspection signal corresponding to the peak voltage of a signal corresponding to the detection, and inspecting an optical disk device based on the inspection signal.