JPH09219056A - Disk reproducing method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable reproduction of plural kinds of disk having different reflectance with a common device by switching gain of a RF signal reproducing circuit, a focus system and a tracking servo system in accordance with reflectance of a disk. SOLUTION: When a disk is loaded and a reproducing key is operated, a discriminating means 23 starts up/down operation of a pickup by a driving means 18. When a loaded disk is a CD-ROM disk, as its reflectance is high, it approaches near the disk focus point and a RF reproduced signal level reaches Vref, the discriminating means 23 detects it, sends a signal to a control means 24, and operates a gain switching means 6. When a loaded disk is a CD-E disk, as reflectance is low, the discriminating means 23 detects it, sends a signal to the control means 24, operates the gain switching means 6 and increases gain of each section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk reproducing method and an apparatus using an optical pickup, and more particularly to a plurality of kinds of disks having different light reflectances, for example, a CD-disk.
The present invention relates to a disc reproducing method and device suitable for reproducing a ROM disc, a CD-E disc, and the like.

[0002]

2. Description of the Related Art A CD (compact disk) player has been practically used for a long time, and in recent years, a so-called CD-ROM in which a CD is applied as a personal computer peripheral device has been rapidly spreading.

On the other hand, as a new medium, CD-E (rewritable disc) is being developed, and its practical use is planned in the near future.

FIG. 5 is a principle block diagram of an optical pickup for reproducing a disc. Reference numeral 1 is an optical disk which rotates about an axis 50. A laser diode 51 is used as a light source, and its light beam is focused on the recording surface of the disk 1 through a lens barrel 56 including a collimator lens system 52, a beam splitter 53, a mirror 55 and an objective lens system (not shown). The reflected light from the disc 1 passes through 56, 55 and 53 to form a light spot on the photodetector 54. The lens barrel 56 is supported by a spring 57, and a coil 58 is attached. Since the magnetic field of the magnet 59 acts on the lens barrel 58, the lens barrel 56 is moved by receiving a force by passing a current through the coil. By changing the direction of the coil,
This force is generated in the focus direction (vertical direction) and the tracking direction (horizontal direction). CD that controls these two directions
-In a ROM actuator, two coils are attached. In FIG. 5, only one coil is shown for simplification of description. That is, it is a model of a one-dimensional actuator.

FIGS. 6 to 8 show the detection principle configuration of the RF signal, the focus servo error signal Fer, and the tracking servo error signal Ter using the pickup of FIG. 5 and the operation waveforms thereof. Although only one light beam is shown in FIG. 5, the well-known 3 widely used
In the beam system, a diffraction grating (not shown) is used to generate one beam for detecting the RF signal and the error signal for the focus servo and two beams for detecting the error signal for the tracking servo. Depending on the detector 54
In addition, two divided detectors (A to D) for detecting the RF signal and the error signal for focus servo and two divided detectors (E and F) for detecting the error signal for tracking servo are arranged.

Although the principle of the three-beam system is well known and the details are omitted, the RF signal is obtained by adding the optical output currents of the four-divided detector as shown in FIG. 6, and the error signal Fer for the focus servo is obtained. As shown in FIG. 7, the difference between the diagonal sum signals of the four-divided detector is calculated, and the tracking servo error signal Ter is further generated by calculating the difference of the optical output currents of the two-divided detector as shown in FIG. .

On the other hand, in the disk reproduction in the CD-RO apparatus, when the reproduction command key is operated as shown in FIG. 9A, the lens barrel under self-weighting shown in FIG. 5, that is, the objective lens is exclusively used. The drive circuit of FIG. 7 moves up / down as shown in (b) and detects the focus pull-in operation range (FOK signal) based on the reproduction level of the RF signal rising as shown in (d), and then the detection circuit of FIG. The zero-crossing point of the sinusoidal error signal Fer obtained in step 1, that is, the in-focus point is detected, and the focus servo system is controlled to close at the timing t1 shown in (f). Then, control is performed to shift to tracking servo control. Be seen.

[0008]

The conventional CD
There is a problem that the above-mentioned CD-E disc cannot be reproduced in the ROM device.

That is, the CD-E disc has a light reflectance of 1/4 to 1/5 with respect to the CD-ROM disc due to its composition.
It is said that even if focus up / down control is performed as indicated by broken lines in FIGS. 9B and 9C, R
The level of the F signal is too low to reach the detection level Vref,
Therefore, it is not possible to detect the FOK signal, that is, even that the disc is loaded, and it is not possible to bring the apparatus into the reproduction state.

Further, even if the FOK signal is detected, the focus and tracking servo error signal detection sensitivity is lowered due to the decrease in the disk reflectance, so that not only the servo control becomes unstable but also the RF signal level. As a result, the error rate of the reproduced data is deteriorated due to the decrease of the signal, and normal signal reproduction cannot be performed.

The present invention has been made to solve the above problems, and an object thereof is to make it possible to reproduce a disc having a low light reflectance such as a CD-E, for example, a CD-ROM. DISCLOSURE OF THE INVENTION PROBLEM TO BE SOLVED: To provide a disc reproducing apparatus and a method thereof capable of reproducing plural kinds of discs having different light reflectances such as a CD-E.

[0012]

DISCLOSURE OF THE INVENTION A disk reproducing method according to the present invention for solving the above-mentioned problems is provided when an optical information reading device such as an optical pickup or the like controls an up / down drive centering on a focus point of a disk. When the level of the information reproduction signal from the information reading device is lower than at least a reference value, the focus and tracking servo gain of the information reading unit and the gain of the information reproduction signal are changed from the first gain to the first gain. It is characterized in that the disc is reproduced by switching to a higher second gain.

When the level of the information reproducing signal is at least higher than the reference value, the focus and tracking servo gain of the information reading section and the gain of the information reproducing signal are lower than the first gain and lower than the first gain. The disc may be reproduced by switching the gain to 2.

Further, when the level of the information reproduction signal from the information reading device at the time of up / down drive control centered on the focal point of the disk of the information reading device is at least lower than the reference value, The up / down drive control is interrupted, and the focus and tracking servo gain of the information reading section and the gain of the information reproduction signal are switched from the first gain to the second gain higher than the first gain, and then, When the up / down drive control of the information reading device is restarted, subsequently, when the signal indicating that the information reproducing signal has reached the reference value and indicating the disk mounting is detected, and the focus error signal detects the in-focus point, the focus servo is performed. , Then the tracking servo pull-in control may be performed to play the disc. .

Further, the disk reproducing apparatus according to the present invention,
Each of the focus and tracking servo of the information reading section and the information reproduction signal is controlled in accordance with the level of the information reproduction signal from the information reading apparatus at the time of up / down drive control centering on the disc focus of the information reading apparatus. It is characterized in that a plurality of types of discs having different light reflectances can be reproduced by switching the gain to at least a predetermined first or second gain.

In the above-mentioned apparatus, a drive means for up / down driving control of the information reading apparatus up and down around a focal point of the disk, and the information reading at the time of up / down driving control of the information reading apparatus by the driving means. Control means for outputting a control signal according to the comparison result of the information reproduction signal level from the device and a reference value, and a control signal from the control means for receiving the information reproduction signal, focus and tracking of the information reading device. Gain switching means for switching and controlling each gain of the servo, wherein the control means outputs a first control signal when the information reproduction level is higher than a reference value, and outputs a first control signal when the information reproduction level is lower than the reference value. Two
The gain switching means sets each gain to a first gain when the first control signal is received from the control means, and the gain control means outputs the second control signal. It may be configured to switch and control the first or second gain so that each gain is set to a second gain that is larger than the first gain when receiving.

The control means is configured to control the gain switching means after a predetermined number of up / down driving operations of the information reading device by the driving means or a predetermined time has elapsed. May be.

Further, the gain switching means may be configured so that the gain of the information reproduction signal, the focus switching of the information reading device and the gain switching value of the tracking servo gain are set to the same value.

Furthermore, the control means may be arranged to hold the output control signal until the disk is removed from the apparatus.

[0020]

1 is a block diagram of a CD-ROM disc reproducing apparatus showing an embodiment of the present invention. In the figure, 1 is a disc, 2 is a disc motor, 3 is a disc motor drive circuit, 4 is an optical pickup, 5 is a feed control mechanism for moving the pickup 4 in the disc radial direction, 6 is an RF signal reproducing circuit 7, Gain switching means of the focus servo error signal detection circuit 8 and the tracking servo error signal detection circuit 9, 10 is an RF signal demodulation circuit, 11 is a signal processing circuit, 12 is a CD-ROM decoder, 13 is its output terminal, and 14 is Audio playback circuit,
Reference numeral 15 is its output terminal, 16 is a phase compensation circuit for a focus servo system, 17 is a control amplifier, 18 is a focus up / down drive circuit, 19 is a focusing actuator coil, 20 is a phase compensation circuit for a tracking servo system, and 21 is a control amplifier. , 22 are tracking actuator coils. The actuator coils 19 and 22 are included in the optical pickup 4. Also,
The audio reproducing circuit and the like are not directly related to the gist of the present invention, but are shown together.

Next, the operation and action of the disc reproducing apparatus according to the embodiment of the present invention shown in FIG. 1 will be described below.

The drive means 18 outputs a control signal U / D shown in FIG. 9B so as to sweep the optical pickup 4 up and down around the disc focusing point in response to the control start command S1 of the identification means 23. Specifically, the U / D signal is configured to switch between positive and negative constant currents and output, and the focus actuator coil 19 is alternately driven via the control amplifier 17 to vertically move the pickup.

The identification means 23 is composed of, for example, a microprocessor for controlling the apparatus, and outputs an output S1 for instructing the drive means 18 to start control when a reproduction command key (not shown) is operated. The signal level RF output from the RF signal reproducing circuit 6 is monitored during the up / down control of the pickup by the drive circuit 18, and when the RF level exceeds a predetermined reference value Vref as shown in FIG. 9C. Outputs an identification signal Ed of "H", "L" when it does not exceed Vref even after repeating up / down a predetermined number of times or a predetermined time. Furthermore, the identification means 2
Reference numeral 3 also monitors the focus servo error signal Fer, and operates to output the focus servo control start command signal Fon to the control amplifier 17 when Ed output "H", that is, when the zero cross point of Fer is detected in the state where the FOK signal is detected. .

As a result, after the output of Fon, the up / down operation by the driving means 18 is stopped and the focus servo system is closed, and then the tracking servo system is closed to start the servo operation of the pickup and the disk reproduction is performed. .

The reference voltage V for identifying the RF signal level
The ref is set to a value suitable for a normal CD-ROM disc so that the reproduction RF level will exceed this when the disc is reproduced.

The control means 24 detects the identification signal Ed from the identification means 23, and when Ed is "H", "H", Ed.
When is "L", the control signal Es of "L" is output.
The control means 24 has a function of storing the control signal Es, and when the disc is mounted and the drive means 18 controls the up / down of the first pickup, the identification means 2 is provided.
The first identification signal Ed output from the device 3 is identified and stored, and the control signal Es is held until the disc is removed.

The gain switching means 6 operates to switch and control the gain, focus and tracking servo gain of the information reproduction signal output from the pickup 4.

FIG. 2 shows an example of a concrete configuration of the gain switching means 6. In the figure, 90 to 94 are changeover switches, 60 'to 63', 66 'to 69' and 7
Reference numerals 9'and 81 'denote resistors, and the other parts denoted by the same reference numerals as those in FIGS. 6 to 8 are the same.

The gain switching means 6 shown in FIG.
In this example, the reproduction gain of the signal and the gains of the focus and tracking servos are switched by controlling the gain of the detection circuit in the first stage.

That is, the resistors 60 'to 63' group have the same ratio as the resistors 60 to 63 group, specifically, the value of the resistors 60 'to 63' group is about 1/5 with respect to the resistors 60 to 63 group. Is set to. Similarly, the resistances 66 'to 69' and 79'81 'are similarly arranged in the resistances 66 to 69 and 7'.
The value is set to about 1/5 for the 9 and 81 groups, and RF is controlled by controlling the changeover switches 90 to 94.
The signal reproduction gain, focus and tracking servo gain are uniformly switched and controlled according to the resistance setting ratio.

The change-over switches 90 to 94 are controlled by the control signal Es of the control means 24. When the dead fish signal Es is "H", the contact is a side in the figure, and when it is "L", it is b in the figure. Works to close to the side. As a result, the control signal E
When s is “H”, RF signal reproduction gain, focus and tracking servo gain are low, and conversely Es is “L”.
In the case of, the gain works higher. Of course, the switching width of the gain is equal to the switching resistance ratio.

With this structure, when the disc is loaded and the reproduction command key is operated, the identification means 23 is driven by the drive means 1.
The control command S1 is issued to the control unit 8 and the drive means 18 starts the up / down operation of the pickup.

If the mounted disk is a CD-ROM disk, its optical reflectance is high as described above, so that the RF reproduction signal level becomes Vref when the pickup approaches the vicinity of the focus point of the disk by the up control. Then, the identification means 23 detects this and outputs "H" as the identification signal Ed to the control means 24. Thereby, the gain switching means 6
Acts to reduce the RF signal reproduction gain, focus and tracking servo gain, and thereafter in this state the identification means 2
At the time point 3 detects the zero-cross point of the focus error signal Fer, the focus servo pull-in is performed, and then the tracking servo pull-in control is performed, and the disc reproduction is performed by the same operation as the conventional device.

When the mounted disc is a CD-E disc, the light reflectance thereof is reduced to about 1/5 of that of the CD-ROM disc. Fig. 9
As shown by the broken line in (c), the RF reproduction signal level is Vre
never reach f. Even if the pick-up / down of the pickup is repeated a predetermined number of times or a predetermined time by the driving means 18, R
When the F signal does not reach Vref, the identification means 23 detects this and issues a control command to the drive means 18 to interrupt the up / down control of the pickup once, and at the same time, the identification means Ed to the control means 24 as the identification signal Ed. Output "L". As a result, the gain switching means 6 functions to increase the RF signal reproduction gain, focus and tracking servo gain. That is, the RF signal reproduction gain, the focus and tracking servo error signal detection gain are uniformly distributed in the CD-ROM.
It is 5 times higher than that of a disc.

Then, the identification means 23 is again driven by the drive means 18.
A control command S1 is issued to the drive means 18 and the up / down operation of the pickup is restarted by the driving means 18. At this time, as the control output Es of the control means 24, "L" is stored and output, and since the RF signal reproduction gain is increased to 5 times by the gain switching means 6, the pickup is the same as in the case of the CD-ROM disc. When approaching the focus point of the disk, the RF reproduction signal level reaches Vref, the FOK signal shown in FIG. 9D is detected, and the discriminating means 23 causes the focus error signal Fe.
When the zero cross point of r is detected, focus servo pull-in and tracking servo pull-in control are performed, and disc reproduction is performed in the same manner as a CD-ROM disc.

In the embodiment shown in FIG. 1, the focus servo error signal Fer is generated independently from the 4-division detector 54 of the pickup 4.
Usually, it may be generated after passing through the RF signal reproducing circuit.

FIG. 3 is a block diagram of a disk reproducing apparatus showing another embodiment of the present invention in such a case, and FIG. 4 is a specific configuration example of the gain switching means 6. In the figure, 95 and 96 are changeover switches, and 9
7, 98, 101, 102 and 103 are resistors, 99,
Reference numerals 100 and 104 denote operational amplifiers, and the other parts denoted by the same reference numerals as those in FIGS. 1 and 2 indicate the same things, and their operations are also the same.

In FIG. 4, the groups of resistors 60 'to 63' have the same ratio as the groups of resistors 60 to 63, specifically, the groups of resistors 60 'to 63 to the groups of resistors 60' to 63 are similar to the embodiment of FIG. The 63 'group is set to a value of about 1/5.

The changeover switches 95 and 96 are controlled by the control signal Es of the control means 24, and the control signal Es
When the value is "H", the contact closes to the side a in the figure, and when the value is "L", the contact closes to the side b. As a result, when the control signal Es is "H", the RF signal reproduction gain becomes low, and conversely, when the control signal Es is "L", the gain becomes high. In synchronization with this, the focus servo gain changes equally. That is,
By controlling the RF signal reproduction gain, it is possible to commonly control the focus servo gain at the same time.

The embodiments of the present invention have been described above.
Although the identification means 23 and the control means 24 are separately provided in the embodiments of FIGS. 1 and 3, the configuration is not particularly limited, and for example, the identification means 23 and the control means 2 may be provided.
It is easily possible to provide the four functions and make them common. Further, although the focus and tracking servo gains are controlled by switching the gains of the error signal detection circuit, this is not particularly limited, and for example, the gains of the control amplifiers of the focus and tracking servo systems are switched and controlled. Needless to say, similar control is possible even with this configuration.

Further, in the present embodiment, the three-beam system has been described as an example of the pickup, but the present invention is not limited to this, and it goes without saying that the present invention can be similarly applied to a well-known two-beam system pickup.

Further, in the present embodiment, in the case of a disc having a low light reflectance, the up / down control of the pickup is temporarily interrupted, the gain switching means resets the gain to a high value, and then the up / down control is performed again. Although the control is performed, this is not particularly limited, and the control can be easily performed without interrupting the operation, and various modifications can be easily performed without changing the gist of the present invention. is there.

[0043]

As described above, according to the present invention, the type of the mounted disc is discriminated by discriminating the RF signal level at the time of focus up / down control, and the RF signal reproducing circuit is discriminated according to the optical reflectance of the disc. The focus and tracking servo system gains are switched. That is, even a CD-E disc having a low light reflectance is automatically detected and controlled so as to maintain the RF signal, the focus and the tracking servo gain at the same level as the CD-ROM disc. It is possible to reproduce a CD-E disc with a common device, that is, to reproduce a plurality of types of discs having different light reflectances with the common device.

[Brief description of drawings]

FIG. 1 is a block diagram of a disc reproducing apparatus showing an embodiment of the present invention.

FIG. 2 is a diagram showing a specific configuration example of a gain switching means 6 in the embodiment of the present invention shown in FIG.

FIG. 3 is a block diagram of a disc reproducing apparatus showing another embodiment of the present invention.

FIG. 4 is a diagram showing a specific configuration example of a gain switching means 6 in another embodiment of the present invention shown in FIG.

FIG. 5 is a diagram showing a basic configuration of an optical pickup.

6 is a diagram showing an RF signal detection circuit applied to the pickup of FIG. 5 and an operation waveform thereof.

7 is a diagram showing a focus servo error signal detection circuit applied to the pickup of FIG. 5 and an operation waveform thereof.

8 is a diagram showing a tracking servo error signal detection circuit applied to the pickup of FIG. 5 and an operation waveform thereof.

FIG. 9 is a diagram illustrating a focus servo pull-in operation.

[Explanation of symbols]

1 ... Disc, 2 ... Disc motor, 4 ... Optical pickup, 6 ... Gain switching means, 18 ... Drive means, 23 ... Identification means, 24 ... Control means.

Claims (9)

[Claims] 1. A disc reproducing method for reproducing information recorded on a disc by using an optical information reading device, said disc reproducing method at the time of up / down drive control centering on a disc focal point of said information reading device. When the level of the information reproducing signal from the information reading device is lower than at least the reference value, the focus and tracking servo gain of the information reading unit and the gain of the information reproducing signal are changed from the first gain to the first gain. A disc reproducing method, characterized in that the disc is reproduced by switching to a high second gain. 2. A disc reproducing method for reproducing information recorded on a disc by using an optical information reading device, said disc reproducing method at the time of up / down drive control centered on a disc focus point of said information reading device. When the level of the information reproduction signal from the information reading device is higher than at least a reference value, the focus and tracking servo gain of the information reading unit and the gain of the information reproduction signal are first adjusted.
The disc reproducing method is characterized in that the disc is reproduced by switching from the first gain to the second gain lower than the first gain. 3. A disc reproducing method for reproducing information recorded on a disc by using an optical information reading device, said disc reproducing method at the time of up / down drive control centered on a disc focal point of said information reading device. When the level of the information reproduction signal from the information reading device is lower than at least a reference value, the up / down drive control of the information reading device is interrupted, and the focus and tracking servo gain of the information reading unit and the information reproduction signal are also interrupted. Is switched from the first gain to a second gain higher than the first gain, and then the up / down drive control of the information reading device is restarted, and then the information reproduction signal reaches the reference value. Then, a signal indicating that the disc is mounted is detected, and when the focus error signal detects the in-focus point, the focus servo is pulled. Inclusive, then the disc playback method, characterized in that for reproducing the disc performs tracking servo pull-in control. 4. The focus and tracking servo of the information reading section and the information according to the level of an information reproduction signal from the information reading apparatus at the time of up / down drive control centering on the disk focus of the information reading apparatus. A disc reproducing apparatus characterized in that a plurality of types of discs having different light reflectances can be reproduced by switching each gain of a reproduction signal to at least a predetermined first or second gain. 5. A disc reproducing apparatus using an optical information reading device, comprising: driving means for vertically driving the information reading device up / down around a focal point of the disc; and the information by the driving means. Control means for outputting a control signal according to the result of comparison between the information reproduction signal level from the information reading device and a reference value during up / down drive control of the reading device, and receiving a control signal from the control means, Gain control means for switching and controlling each gain of the information reproduction signal, focus and tracking servo of the information reading device, the control means performing a first control when the information reproduction level is larger than a reference value. A signal is output and a second control signal is output when the signal is smaller than a reference value. Each of said gain when receiving the serial first control signal is set to the first gain, the first said respective gain when receiving the second control signal
2. The disc reproducing apparatus, wherein the first or second gain is switched and controlled so as to be set to a second gain which is larger than the gain. 6. A disc reproducing apparatus using an optical information reading device, comprising: driving means for vertically driving up / down the information reading device about a disc focusing point, and reproducing by the information reading device. Identifying means for identifying the information reproduction signal level and outputting an identification signal according to the magnitude of the information signal level; and control means for identifying the identification signal output from the identifying means and outputting a control signal. A gain switching unit that receives the control signal output from the control unit and switches and controls the gains of the information reproduction signal and the focus and tracking servo of the information reading device. When an identification signal is detected by the identification means during up / down drive control of the information reading device by the drive means, the control means Therefore, each gain is controlled to be a first gain, and when the identification signal is not detected by the identification means, the control means is controlled to make each gain a second gain. A disk reproducing device characterized by being configured. 7. The control means is configured to control the gain switching means after an up / down drive operation of the information reading device by the drive means is performed a predetermined number of times or a predetermined time has elapsed. 7. The disc reproducing apparatus according to claim 6, which is characterized in that. 8. The gain switching means is configured to set the gain switching values of the gain of the information reproduction signal, the focus of the information reading device and the tracking servo gain to the same value. The disk reproducing device described in. 9. A disc reproducing apparatus, wherein said control means is configured to hold the output control signal until the disc is detached from the device.