JP3031440B2 - Optical disc identification method - 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 disc discriminating method for discriminating the type of an optical disc set in an optical disc apparatus.

[0002]

2. Description of the Related Art Conventionally, there is a CD (compact disk) player as a reproduction-only device using an optical disk. C
The optical disk used in the D player is an optical disk usually called a CD, which is provided with a reflective film of aluminum and has a reflectance of 70% or more, and is configured as a read-only optical disk. And in CD players,
Whether such an optical disk is set or not is determined based on the reflected light signal from the optical pickup.

[0003] In the determination apparatus using such a method, for example, a servo error signal, a servo system sum signal, a reproduction signal, or the like is used as a reflected light signal by a configuration as shown in FIG. 7 compared with the output voltage VR,
The comparison result is output as a logic signal. FIG. 6 shows, together with the focus error signal, the output logic signal of the comparator 6 when the focus error signal is used as the reflected light signal in such a determination device.

As shown in FIG. 6, when the optical disk is set, the signal level always exceeds the reference voltage VR when the focus error signal S51 is output. At this time, the logic signal S52 becomes low level. Become. Therefore, according to such a conventional method, the presence of the optical disk can be confirmed by detecting that the logic signal S52 has a low level.

In recent years, a rewritable CD recorder using a magneto-optical disk, which is a kind of optical disk, has been developed. The reflectivity of this magneto-optical disk is 20%
This is before and after, and is less than half the size of the above-mentioned compact disc for reproduction only. In a rewritable CD recorder, rewriting is performed in a system conforming to the CD format, so that the apparatus can also play back a compact disc for reproduction only. FIG. 7 shows a block diagram of a typical rewritable CD recorder.

At the time of recording, analog audio information is input from an input terminal 43, and A dedicated for audio information is used.
It is converted into digital audio information in the / D converter 40. The converted information is recorded data processing circuit 3
9 is converted into information suitable for recording, and the coil driver 37
Is applied to the coil 34. Then, a modulation magnetic field corresponding to the recorded information is applied to the magneto-optical disk 30 by the coil 34. On the other hand, the laser driver 35 drives the optical pickup 32 in response to a command from the controller 42, and the optical pickup 32 irradiates the optical disc 30 with a high-power light beam, and information is recorded by locally increasing the temperature. . The servo circuit 33 executes focus, tracking, and feed optical servos of the optical pickup 32, and further performs CLV of the spindle motor 31.
(Constant linear velocity) control is also performed.

At the time of reproduction, information recorded on the optical disk 30 is read by an optical pickup 32, and the information is transmitted via a reproduction amplifier 36 to a reproduction data processing circuit 3.
It is led to 8. The reproduction data processing circuit 38 converts the input information into digital audio information and outputs the digital audio information to the D / A converter 41. The D / A converter 41 converts the digital information from the processing circuit 38 into analog audio information and outputs it to an output terminal 44.

Next, a case where a compact disk is set as the disk 30 and information is reproduced will be described. As described above, since the compact disk has a high reflectivity, the laser driver 35 sets the optical power to about one third of that in the case of the magneto-optical disk according to an instruction from the controller 42. Further, the servo circuit 33 and the reproducing amplifier 36
Respectively switch the gain for the compact disc, and the reproduction data processing circuit 38 changes the arithmetic processing. Thereafter, the controller 42 turns on the optical servo, and the optical pickup 32 reads information from the compact disk. The subsequent information flow is the same as in the case of the magneto-optical disk.

As described above, in the rewritable CD recorder, since both optical discs are handled, before the recording / reproducing operation is performed, the loaded optical disc is first used as a read-only compact high-reflectance compact disc or a low-reflective compact disc. It is necessary to determine whether the disk is a magneto-optical disk having a reflectance, and then turn on the optical servo.

As a method of discriminating an optical disc, a method in which the above-described method of confirming the presence or absence of a disc in a CD player can be considered. That is, as shown in FIG. 8, by comparing a plurality of reference voltages and the reflected light signal from the disk at the same time, the intensity of the reflected light signal can be checked and the disk can be determined. FIG. 9 shows various signals when a focus error signal is used as a reflected light signal, that is, a focus error signal S for a magneto-optical disk in order from the top.
61, an output logic signal S62 of the second comparator 13 for a magneto-optical disk, an output logic signal S63 of the first comparator 12 for a magneto-optical disk, a focus error signal S64 for a compact disk, and a compact disk The waveforms of the output logic signal S65 of the second comparator 13 and the output logic signal S66 of the first comparator 12 in the case of a compact disk are shown. In FIG. 9, the voltage VR1 on the vertical axis of the signals S61 and S64.
Is the output voltage of the first reference voltage source 8 shown in FIG.
The voltage VR2 is the output voltage of the second reference voltage source 9.

In a series of operations for moving the objective lens of the optical pickup toward and away from the disk from a distance,
Since the objective lens and the disk obtain the in-focus position twice, a focus error signal appears twice as shown in signals S61 and S64. Then, the difference between the two output levels directly appears as the difference between the logic signals of S62, S63, S65, and S66. That is, in the case of a magneto-optical disk, the first
Only the output of the comparator 12 is at a low level, and in the case of a compact disc, the output logic signals of both the first comparator 12 and the second comparator 13 are at a low level. Therefore, according to the conventional method, it is possible to determine the disk based on the difference between the logic levels of these logic signals.

As another method, it is easily conceivable to discriminate a disk with a configuration as shown in FIG. That is, the peak value of the reflected light signal is obtained by the peak hold circuit 50 and is converted into a digital signal by the general-purpose A / D converter 14. Then, the disc is determined based on the difference between the peak values.

[0013]

Generally, in this type of optical disk apparatus, there is a demand to reduce the size and weight and reduce the cost while maintaining the quality and reliability. However, it is desirable that highly reliable discrimination can be performed with a configuration as simple as possible.

However, the above-described conventional discrimination method has the following problems. That is, (1) In the method in which the reflected light signal is compared with a plurality of reference voltages and determined at the same time, information for determination, that is, signal lines for transmitting the output logic signal of the comparator are required by the number of reference voltages, This increases the number and complexity of signal lines around the controller.

(2) In the method in which the peak value of the reflected light signal is converted into a digital signal for determination, a general-purpose A / D converter is required, which leads to an increase in the cost of the apparatus.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an optical disc discriminating method capable of discriminating a highly reliable optical disc with a simple configuration.

[0017]

According to the first aspect of the present invention, in order to achieve the above-mentioned object, an optical disk discriminating method determines whether an optical disk set in an optical disk apparatus is a reproduction-only or recording / reproduction optical disk. An optical disc discriminating method used in an optical disc apparatus for performing the operation based on the intensity of a reflected light signal from an optical disc obtained by a pickup, wherein a peak hold circuit for outputting a peak hold signal with the reflected light signal as an input; , A reference signal generating means for outputting a reference signal of a predetermined level, and a comparing means for comparing the reference signal with the peak hold signal, and a peak hold signal obtained as a result of comparison by the comparing means. Is determined on the basis of the time required to attenuate to the level of the reference signal.

In order to achieve the above object, the optical disc discrimination method according to the second invention of the present application determines whether an optical disc set in an optical disc device is for reproduction only or for recording and reproduction from an optical disc obtained by an optical pickup. An optical disc discriminating method used in an optical disc apparatus for performing the operation based on the intensity of the reflected light signal, wherein a reference signal generating means for sequentially outputting a plurality of reference signals having predetermined levels different from each other; and sequentially outputting the reference signal and the reflected light signal. Comparing means for comparing and outputting a comparison result as a time-series digital pulse, wherein the determination is made based on the number of digital pulses.

[0019]

According to the optical disc discrimination method of the first invention of the present application,
The peak hold circuit receives the reflected light signal from the optical disk obtained by the optical pickup as an input, and
Output the output signal. On the other hand, the reference signal generating means outputs a reference signal of a predetermined level. The comparing means compares the reference signal with the peak hold signal.

Here, when the set optical disk is for reproduction only, the peak level of the reflected light signal is high,
Therefore, the peak hold signal maintains the high level for a long time, and accordingly, the comparing means outputs a comparison result in which the predetermined level continues for a long time, for example, in the form of a logic signal.

On the other hand, when the set optical disk is for recording and reproduction, the peak level of the reflected light signal is low,
Accordingly, the peak hold signal maintains the high level only for a short time, and accordingly, the comparing means outputs a comparison result in which the high level continues only for a short time, for example, in the form of a logic signal.

Therefore, when the optical disk is dedicated to reproduction, the time required for the peak hold signal to attenuate to the level of the reference signal, which is obtained as a result of comparison by the comparing means, becomes longer. If it is
Such a decay time is shortened.

Therefore, according to the optical disk discrimination method of the first invention, it is determined whether the optical disk is for reproduction only or for recording / reproduction based on the decay time that changes according to the type of the optical disk. be able to.

As a result, with a relatively simple configuration utilizing a reflected light signal from an optical disk obtained by an optical pickup, it is possible to determine with high reliability whether the optical disk is for reproduction only or for recording and reproduction. be able to.

According to the optical disk discrimination method of the second invention of the present application, the reference signal generating means sequentially outputs a plurality of reference signals having predetermined levels different from each other. The comparing means sequentially compares the reference signal and the reflected light signal and outputs a result of the comparison as a time-series digital pulse.

Here, the level of the reflected light signal is high when the set optical disk is for reproduction only, and the level of the reflected light signal is low when the set optical disk is for recording and reproduction. For this reason, the reference signal generating means sequentially generates reference signals having different levels in a range extending from at least one of the low reflected light signal level of the recording / reproducing optical disc to the high reflected light signal level of the read-only optical disc. With this configuration, even if the level of the reference signal changes, the comparison unit determines whether the optical disk is dedicated to reproduction or recording / reproduction as a result of the comparison, with a constant level corresponding to the successive generation of the reference signal. The output of the digital pulse is stopped or the output of the digital pulse is stopped according to the change in the level of the reference signal.

Therefore, according to the optical disk discrimination method of the second invention, the type of the optical disk differs as described above.
Based on the number of digital pulses from the comparing means, it is possible to determine whether the optical disk is for reproduction only or for recording and reproduction.

As a result, with a relatively simple configuration utilizing the reflected light signal from the optical disk obtained by the optical pickup, it is possible to determine with high reliability whether the optical disk is for reproduction only or for recording and reproduction. be able to.

The operation of the present invention will be more apparent from the following examples of the present invention, and further other effects of the present invention will be apparent.

[0030]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an optical disc discriminating apparatus according to a first embodiment of the present invention.

Referring to FIG. 1, the optical disc discriminating apparatus includes a peak hold circuit 5, a comparator 6 as an example of a comparing means, and a reference voltage source 7 as an example of a reference signal generating means.

Here, the peak hold circuit 5 includes operational amplifiers 1 and 4, a diode 2, and a capacitor 3. The output terminal of the operational amplifier 1 is connected to the inverting input terminal of the operational amplifier 1, and a focus error signal is input to the non-inverting input terminal as a reflected light signal from an optical disk device (not shown). The anode of the diode 2 is connected to the output terminal of the operational amplifier 1, and the cathode is connected to the non-inverting input terminal of the operational amplifier 4. The capacitor 3 is connected between the non-inverting input terminal of the operational amplifier 4 and the ground, and the output terminal of the operational amplifier 4 is connected to the inverting input terminal of the operational amplifier 4. The comparator 6 compares the output voltage of the operational amplifier 4 with the reference voltage VR output from the reference voltage source 7, and when the former is lower than the latter, it is at a high level, and when the former is higher than the latter, it is at a low level. Outputs a logic signal.

Next, the operation of this embodiment configured as described above will be described with reference to FIG.

In FIG. 2, S11 and S12 indicate the output signal of the peak hold circuit 5 and the output logic signal of the comparator 6, respectively, when a recording / reproducing magneto-optical disc is set as the optical disc. On the other hand, S13 and S14 are respectively the output signal of the peak hold circuit 5 and the comparator 6 when the read-only compact disc is set as the optical disc.
3 shows an output logic signal. The voltages VP1 and VP2 shown on the vertical axis for the signals S11 and S13 are the peak voltages of the output signals of the peak hold circuit 5 in each case. Also, waveforms F11 and F12 indicated by dotted lines represent focus error signals, respectively.

The peak hold circuit 5 holds the peak voltage of the focus error signal. However, the charge accumulated in the capacitor 3 is discharged through the input impedance of the operational amplifier 4, or the current flows in the diode 2 in the opposite direction and is discharged. In practice, the output voltage of the peak hold circuit 5 actually decreases gradually with time after the focus error signal has a peak like the signals S11 and S13. The gradually decreasing voltage VD is generally expressed by the following equation.

[0036]

## EQU1 ## where t is time, I1 is a leak current causing discharge of the capacitor 3, and CH is the capacity of the capacitor 3. Therefore, the time required to reach the reference voltage VR from the peak value VP1 is represented by the following equation.

[0037]

## EQU2 ## t = (VP1-VR) .CH / I1 Since VR, CH and I1 are constant in the above equation, the time t is proportional to the peak value. Since the time t predominantly determines the low-level pulse width of the logic signal output from the comparator 6, the peak value can be detected by measuring the low-level period. As can be seen from the signals S12 and S14 shown in FIG. 2, the low-level period is short in the case of a magneto-optical disk, while the low-level period is extremely long in the case of a compact disk, and the two can be clearly distinguished. . Therefore, when the period during which the logic signal output from the comparator 6 is at the low level is short, it can be determined that the magneto-optical disk is set, and on the other hand, the comparator 6
If the period during which the logic signal output by the low level is low is long, it can be determined that the compact disc is set.

The measurement of the period during which the output logic signal of the comparator 6 is at the low level can be performed, for example, by performing a counting operation during the low level on the basis of an appropriate clock by a controller of a device constituted by a CPU. Of course, a dedicated counter may be provided to count a predetermined clock. It is desirable that the values of the reference voltages VR, CH, and I1 be set so that the low-level period of the logic signal is shorter than the time interval between two consecutive focus error signals.

As described above, in the optical disc discriminating apparatus of this embodiment, it is not necessary to use an A / D converter as in the prior art, and information for discrimination is obtained from only one comparator. Only one signal line for transmission is required. In addition, when the disk is not set, the output logic signal of the comparator 6 does not become low level, which makes it possible to determine that the disk is not set, which is extremely advantageous.

Next, an optical disc discriminating apparatus according to a second embodiment of the present invention will be described.

As shown in FIG. 3, the optical disc discriminating apparatus includes a first reference voltage source 8, a second reference voltage source 9, a switch 11, and a switching control unit 1 which constitute an example of a reference signal generating means.
0 and a comparator 6 which constitutes an example of the comparing means. The first reference voltage source 8 has a first reference voltage VR1.
And the second reference voltage source 9 outputs a second reference voltage VR2 higher than the first reference voltage VR1. The switch 11 selects and outputs one of these two voltages based on the control of the switching control unit 10.

On the other hand, the comparator 6 compares the reference voltage output from the switch 11 with the reflected light signal which is a focus error signal. When the former is higher than the latter, the comparator is at a low level, and when the former is lower than the latter, it is lower. Outputs a high-level logic signal. The switching control unit 10 causes the switch 11 to switch the reference voltages VR1 and VR2 at the rise of the logic signal output from the comparator 6.

Next, the operation of the present embodiment configured as described above will be described.

First, when the magneto-optical disk is set, the comparator 6 outputs a high-level logic signal when no focus error signal is input, as shown at S22 in FIG. When the focus error signal is input as shown in FIG. 5 and the voltage rises and reaches the first reference voltage VR1, the logic signal changes to a low level.
After that, the focus error signal drops through the peak value,
When the voltage falls below the voltage VR1, the logic signal goes high again.
At this time, the switching control unit 10 controls the switch 11 to select the reference voltage VR2, and as a result, the comparator 6 is supplied with the second reference voltage VR2. On the other hand, the focus error signal returns to the 0 level via the bottom value.

Thereafter, the next focus error signal is input to the comparator 6. The second reference voltage VR1 higher than the first reference voltage is input to the comparator 6, and the focus error signal is input to the voltage VR2. , The logic signal output from the comparator 6 never goes low.

On the other hand, when the compact disk is set, the comparator 6 operates in the same manner as when the magneto-optical disk is set when no focus error signal is input as shown in S24, as in the case where the magneto-optical disk is set. Signal is being output. Then, as shown in S23, the focus error signal is input, the voltage of the focus error signal increases, and the first reference voltage V
When reaching R1, the logic signal changes to low level. After that, when the focus error signal decreases through the peak value and falls below the voltage VR1, the logic signal goes high again. At this time, the switching control unit 10 controls the switch 11 to select the reference voltage VR2, and as a result, the comparator 6 is supplied with the second reference voltage VR2. On the other hand, the focus error signal returns to the 0 level via the bottom value.

Thereafter, when the next focus error signal is input to the comparator 6 and its voltage value increases, the comparator 6 receives the second reference voltage VR1 higher than the first reference voltage. Since the focus error signal rises beyond the voltage VR2, the logic signal output from the comparator 6 changes to a low level. After that, when the focus error signal decreases through the peak value and falls below the voltage VR1, the logic signal goes high again.

That is, in a series of operations for moving the objective lens of the optical pickup toward and away from the disk from a distance, the logic signal goes low only once in the case of a magneto-optical disk, but in the case of a compact disk. It goes low twice. Therefore, by counting the number of low-level pulses of the logic signal, if the number of pulses is 1, it can be determined that the magneto-optical disk is set, while if the number of pulses is 2, the compact disk is set. You can judge that it is done.

As described above, in the optical disk discriminating apparatus of this embodiment, it is not necessary to use an A / D converter as in the prior art, and information for discrimination is obtained from only one comparator. Only one signal line for transmission is required. In the state where the disk is not set, the output logic signal of the comparator 6 never goes to the low level, so that it can be determined that the disk is not set, which is extremely advantageous.

In these embodiments, the focus error signal is used as the reflected light signal. However, as described above, the signal level representing the reflectivity of the disk, such as a servo error signal, a servo sum signal, a reproduction signal, etc. Any reflected signal can be used.

[0051]

As described above in detail, according to the optical disk discrimination method of the first invention of the present application, a peak hold circuit for outputting a peak hold signal with a reflected light signal as an input, A reference signal generating means for outputting the reference signal; and a comparing means for comparing the reference signal with the peak hold signal, wherein the peak hold signal obtained as a result of the comparison by the comparing means is the reference signal. Since the discrimination is performed based on the time to decay to the level, a relatively simple configuration using the reflected light signal from the optical disc obtained by the optical pickup allows the optical disc to be used only for reproduction or for recording / reproduction. The determination as to whether or not there is can be made with high reliability.

Further, according to the first invention, the A / D converter is unnecessary as in the above-mentioned conventional example, and the comparison means can be constituted by one comparator. Only one signal line is required. Further, it is possible to determine whether or not the optical disc is set, based on whether or not the comparison means outputs a logic signal of a predetermined level.

According to the optical disk discrimination method of the second invention of the present application, the reference signal generating means for sequentially outputting a plurality of reference signals of different predetermined levels, the reference signal and the reflected light signal are sequentially compared, and the comparison result is obtained. Comparing means for outputting as a series of digital pulses, and performing the determination based on the number of digital pulses, so that a relatively simple method using a reflected light signal from an optical disc obtained by an optical pickup is used. With this configuration, it is possible to determine with high reliability whether the optical disk is for reproduction only or for recording and reproduction.

According to the second aspect of the present invention, the A / D converter is unnecessary as in the above-described conventional example, and the information for discrimination can be constituted by one comparing means, so that the information is transmitted. Only one signal line is required. Further, it is possible to determine whether or not the optical disk is set, based on whether or not the comparing means does not output the digital pulse even once.

As described above, according to the present invention, it is possible to realize an extremely convenient optical disk apparatus which is highly reliable, compact, lightweight and inexpensive, and can record and reproduce a read-only CD and a recording / reproducing magneto-optical disk.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an optical disc discriminating apparatus according to a first embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the optical disc discriminating apparatus of FIG. 1;

FIG. 3 is a block diagram showing an optical disc discriminating apparatus according to a second embodiment of the present invention.

FIG. 4 is a timing chart for explaining the operation of the optical disc discriminating apparatus of FIG. 3;

FIG. 5 is a block diagram showing an example of a conventional disk presence / absence determination device that determines whether a disk is set.

FIG. 6 is a timing chart for explaining the operation of the determination device in FIG. 5;

FIG. 7 is a block diagram showing an example of a rewritable CD recorder.

FIG. 8 is a block diagram showing an example of a conventional optical disc discriminating apparatus.

FIG. 9 is a timing chart for explaining the operation of the optical disc discriminating apparatus of FIG. 8;

FIG. 10 is a block diagram showing another example of a conventional optical disc discriminating apparatus.

[Explanation of symbols]

 1, 4 operational amplifier 2 diode 3 capacitor 5 peak hold circuit 6 comparator 7 reference voltage source 8 first reference voltage source 9 second reference voltage source 10 switching control unit 11 switch

Continuation of front page (56) References JP-A-62-76061 (JP, A) JP-A-4-115357 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7 / 00-7/013 G11B 11/105 581 G11B 19/12 501

Claims (2)

(57) [Claims] An optical disk set in an optical disk device is used for determining whether an optical disk set for read-only or for recording / reproduction is based on the intensity of a reflected light signal from the optical disk obtained by an optical pickup. A peak-hold circuit that outputs a peak-hold signal with the reflected light signal as input, reference signal generation means that outputs a reference signal of a predetermined level, Comparing means for comparing the peak hold signal with the peak hold signal, wherein the discrimination is made based on the time for which the peak hold signal obtained as a result of comparison by the comparison means attenuates to the level of the reference signal. An optical disc discrimination method characterized by performing the following. 2. An optical disk drive according to claim 1, wherein said optical disk set in said optical disk drive is used for reproduction only or for recording / reproduction based on the intensity of a reflected light signal from said optical disk obtained by an optical pickup. A reference signal generating means for sequentially outputting a plurality of reference signals having predetermined levels different from each other, and sequentially comparing the reference signal and the reflected light signal to obtain a comparison result as a time-series digital pulse. An optical disc discriminating method, comprising a comparing means for outputting the discriminated information, wherein the discriminating is performed based on the number of the digital pulses.