JP2004006035A - Optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a starting period of a drive by discriminating a disk in advance even when a CD or a digital video disk (DVD) that are not accommodated in a cartridge is inserted and to prevent information from being destroyed even when a CD-R disk is inserted into the disk drive by mistake. <P>SOLUTION: A microcomputer 147 switches an optical system to that for a DVD when a disk is loaded. After a focusing lens 110 is kept away from a disk 100, the focusing lens is gradually brought closer to the disk to calculate the maximum values of an FE signal, an ENV signal and an AS1 signal. If the AS1 signal is not higher than a prescribed level, the disk 100 is determined to be a CD-R disk and ejects it from the optical disk drive. The microcomputer 147 calculates ENV/AS1, and when the ENV/AS1 is not larger than a prescribed value, the microcomputer 147 determines the disk 100 to be a CD and switches to an actuator 127 being an optical system for CD and a focusing lens 126. When the ENV/AS1 surpasses the prescribed value, the disk 100 is determined to be a DVD. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an optical disk device capable of reproducing a plurality of types of disks such as a compact disk (hereinafter, referred to as a CD) and a digital video disk (hereinafter, referred to as a DVD).

2. Description of the Related Art There is an optical disk device that focuses and irradiates a light beam generated by a laser onto a rotating disk and reproduces a signal recorded on the disk.

FIG. 25 is an enlarged view of a general CD, that is, a compact disc. A pit row P is formed on the disk, and each forms a track.

(4) Aluminum is deposited as a reflective film on the surface of the disk where the pits are formed, that is, on the information surface. The disk is irradiated with a light beam from the lower side of the figure. The track interval, that is, the track pitch is 1.6 μm, and the tracks are provided spirally. When reproducing the information recorded on the track, the focusing control is performed so that the focal point of the light beam is always located on the information surface, that is, the portion where the aluminum reflective film exists, and the focal point of the light beam is on the track. The tracking control is performed so as to be positioned at. The disc has a diameter of about 120 mm and a substrate thickness of 1.2 mm, while the wavelength of the light beam is 780 nm.

In recent years, a disk with a higher recording density, for example, a digital video disk (hereinafter referred to as a DVD) on which digital image data is recorded has been proposed. Hereinafter, a DVD will be described as an example of a disk having a high recording density. However, in the present invention, the disk having the increased recording density is not limited to the DVD.

DVDs have a recording density about five times that of the above-mentioned CDs. In order to achieve this recording density, the track pitch is set to 0.74 μm and the linear recording density (the number of data per unit length on the track) is increased. In order to cope with the improvement of the recording density, the wavelength of the light beam is set to be as short as 650 nm. Further, in order to stably reproduce information recorded on the disk even if the disk is inclined, the base material thickness is set to 0.6 mm, and the base material thickness is smaller than that of a CD. Incidentally, the diameter of the disc is almost the same as that of the CD.

Hereinafter, this disc is referred to as a single-layer DVD. In addition to a single-layer DVD, a DVD having a structure shown in FIG. 26, that is, a double-layer DVD is available. Also in this two-layer DVD, the light beam is irradiated from the lower side, and similarly to the one-layer DVD, there is a surface on which information is recorded at 0.6 mm from the lower side. It is called a layer. A reflective film such as gold is used for the first layer, and its reflectivity is as low as about 35%. Therefore, a part of the light beam passes through the first layer, and the first layer becomes the first information surface. Further, on the first layer, there is a surface on which information is recorded with a 40 μm intermediate layer interposed therebetween, and this is hereinafter referred to as a second layer. The light beam that has passed through the first layer is reflected by the second layer, passes through the intermediate layer, the first layer, and the base material, and the second layer becomes the second information surface. Accordingly, the information of the first layer and the information of the second layer can be reproduced. The second layer is made of aluminum or the like, and has a reflectance of about 90%. The recording capacity of this disc, that is, the double-layer DVD is about twice that of the single-layer DVD. When reproducing the first information surface of this dual-layer DVD, focusing control is performed on the first information surface, and when reproducing the second information surface, the second information surface is reproduced from the first information surface. After moving the focus to the information surface, focusing control is performed on the second information surface.

When a CD and a DVD are reproduced by the same optical disk device, an optical system for reproducing the CD and an optical system for reproducing the DVD are provided because the substrate thicknesses are different, and switching is performed according to the disk. There is a need to. However, there is a case where neither the CD nor the DVD is built in the cartridge. In this case, a discriminating hole is provided in the cartridge to discriminate the disc, and the optical system is switched accordingly. It is not possible.

Also, when a disk called a CD-R (Compact Disk-Rewritable) (corresponding to an optical system for CD) which can be recorded only once is loaded into an optical disk device, the optical system for DVD is erroneously set. If you use, information may be destroyed.

The reason for this is that a CD-R disc generally uses an organic dye-based material as a recording film, and therefore has a high absorptance at a wavelength of 650 nm, and highly absorbs the light of the wavelength 650 nm, and This is because the system material is destroyed.

As described above, CDs and DVDs may not be built in the cartridge, so that it is not possible to provide a hole for discrimination in the cartridge and thereby discriminate the disc. Therefore, if an optical system for a DVD is used in spite of being a CD, information cannot be normally reproduced from the CD because the substrate thickness is different between the CD and the DVD.

The present invention has been made to solve the conventional problems, and an object of the present invention is to provide an optical disk apparatus capable of discriminating a disk even if the disk is a CD or DVD that is not built in a cartridge.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. Even when a disk called a CD-R that can be recorded only once is inserted into an optical disk device, the disk of the CD-R and the DVD can be used. It is an object of the present invention to provide an optical disk device which can determine the CD-R and does not destroy the organic dye material of the CD-R.

An optical disk device according to the present invention is an optical disk device including an optical system for a disk with a thin base material and an optical system for a disk with a thick base material, and a light beam for reproducing information from an information surface of the disk. Moving means for moving the focal point in a direction perpendicular to the information surface, light detecting means for detecting the amplitude of the information reproduction signal based on the reflected light from the disk, and moving means so that the focal point passes through the information surface. The maximum value of the information reproduction signal amplitude of the light detecting means at the time of driving is obtained, and the maximum value is determined based on the fact that the maximum value is larger than when the loaded disk and the optical system used are different from each other. The disc obtained is provided with a discriminating means for discriminating between a disc having a thick base material and a disc having a thin base material.

Also, an optical disk device according to the present invention is an optical disk device including an optical system for a disk with a thin base material and an optical system for a disk with a thick base material, and reproduces information from the information surface of the disk. Moving means for moving the focal point of the light beam in a direction perpendicular to the information surface, light detecting means for receiving reflected light from the disk, and whether the loaded disk is a disk with a thick or thin substrate Determination means for determining the maximum value AS1Lmax of the output value of the photodetection means and the maximum value ENVmax of the information reproduction signal amplitude by driving the movement means so that the focal point passes through the information surface, Based on the fact that the ratio between the ENVmax and AS1Lmax is different depending on whether the loaded disc and the optical system used match or not, the discrimination means determines the disc loaded. There is obtained by configured to determine substrate thickness of a thick disk or substrate thickness of the thin disk.

In the optical disk device according to the present invention, in the optical disk device, an optical system for reproducing information recorded on the disk is an optical system for a disk having a thin base material.

Further, in the optical disk device according to the present invention, in the optical disk device, when the amount of reflected light from the disk exceeds the predetermined value of the output value of the light detecting unit, the moving unit is controlled to reduce the moving speed of the focal point. It is intended to be.

According to the optical disk device of the present invention, there is provided an optical disk device including an optical system for a disk with a thin base material and an optical system for a disk with a thick base material, and reproduces information from the information surface of the disk. Moving means for moving the focal point of the light beam in a direction perpendicular to the information surface, light detecting means for detecting the amplitude of the information reproduction signal based on the reflected light from the disk, and moving the focal point so as to pass through the information surface The maximum value of the information reproduction signal amplitude of the light detecting means when the means is driven is obtained, and based on the fact that the maximum value is larger than that when the loaded disc and the optical system used are different from each other. Since the loaded disc is provided with a discriminating means for discriminating between a disc having a thick base material and a disc having a thin base material, a disc having a thin base material and a disc having a thick base material have a simple structure. It is possible to determine the door.

Further, according to the optical disk device of the present invention, there is provided an optical disk device including an optical system for a disk with a thin base material and an optical system for a disk with a thick base material. Moving means for moving the focal point of the light beam to be reproduced in a direction perpendicular to the information surface, light detecting means for receiving the reflected light from the disc, and the loaded disc having a thick base material or a thin base material A discriminating means for discriminating whether the disc is a disc, and driving the moving means so that the focal point passes through the information surface to thereby determine the maximum value AS1Lmax of the output value of the light detecting means and the maximum value ENVmax of the amplitude of the information reproduction signal. Then, based on the fact that the ratio between the ENVmax and AS1Lmax is different depending on whether the loaded disc and the used optical system match or not, the discriminating means determines that the disc is loaded. Since disk is configured to determine whether the substrate thickness of a thick disk or substrate thickness of a thin disk, it is possible to distinguish the thick disk of a thin disk and the substrate thickness of the substrate thickness by a simple structure.

Further, according to the optical disk device of the present invention, in the optical disk device, the optical system for reproducing the recorded information of the disk is an optical system for a disk with a thin base material. In this case, the time until the information on the disc can be reproduced is reduced.

Further, according to the optical disk device of the present invention, in the optical disk device, when the amount of light reflected from the disk exceeds the predetermined value of the output value of the light detecting unit, the moving unit is controlled to control the moving speed of the focal point. , The reliability of disc discrimination can be improved.

Embodiment 1 FIG.
Hereinafter, the optical disc device according to the first embodiment of the present invention will be described with reference to FIG.

The optical disc device according to the first embodiment discriminates between a single-layer DVD, a double-layer DVD, a CD, and a CD-R. In FIG. 1, reference numeral 100 denotes a disk, which is placed on a tray 149. Reference numeral 147 denotes a microcomputer (hereinafter, referred to as a microcomputer) which drives the motor 118 to move the tray 149 when the disk 100 is placed on the tray 149, whereby the disk 100 is It is attached to the rotating shaft 102 of the table 101.

The transfer table 104 has a laser 105 (having a wavelength of 650 nm), a coupling lens 106, a polarizing beam splitter 107, a quarter-wave plate 108, a total reflection mirror 109, a photodetector 111, a motor 128, and an actuator. The transfer table 104 is configured to be moved in the radial direction of the disk 100 by a transfer motor 103 such as a linear motor.

The light beam generated by the laser 105 attached to the transfer table 104 is converted into parallel light by a coupling lens 106, and then passes through a polarizing beam splitter 107 and a quarter-wave plate 108. Then, the light is reflected by the total reflection mirror 109, focused on the information surface of the disc 100 by the focusing lens 110, and irradiated. The focusing lens 110 and the actuator 112 are used when reproducing a DVD.

When reproducing a CD, the motor 128 is driven to switch to the CD focusing lens 126 and the actuator 127 in place of the DVD actuator 112 and the focusing lens 110. In a conventional CD-dedicated device, a laser having a wavelength of 780 nm is used for the CD. However, the focusing lens 126 for the CD is designed with the laser 105 having a wavelength of 650 nm and a base material thickness of the CD of 1.2 mm. Have been.

The reflected light reflected by the information surface of the disc 100 passes through a focusing lens 110 and is reflected by a total reflection mirror 109, and is a quarter-wave plate 108, a polarizing beam splitter 107, a detection lens 113, and a cylindrical lens 116. , And irradiates the photodetector 111 divided into four. The focusing lens 110 is attached to a movable part of the actuator 112. The actuator 112 includes a focusing coil, a tracking coil, a focusing permanent magnet, and a tracking permanent magnet. Therefore, when a voltage is applied to the focusing coil (not shown) of the actuator 112 by using the power amplifier circuit 133, a current flows through the coil (focusing coil) and a permanent magnet for focusing (not shown). ) From the magnetic force. Therefore, the focusing lens 110 moves in a direction perpendicular to the surface of the disk 100 (vertical direction in the figure). As described above, the focusing lens 110 is controlled based on the focusing error signal indicating the difference between the focal point of the light beam and the information surface of the disk so that the focal point of the light beam is always located on the information surface of the disk 100. ing.

When a voltage is applied to the tracking coil (not shown) of the actuator 112 by using the power amplifying circuit 136, a current flows through the coil and a magnetic force is applied from a tracking permanent magnet (not shown). Receive. Therefore, the focusing lens 110 moves in the radial direction of the disk 100, that is, in the direction crossing the tracks on the disk 100 (left and right in the figure).

(4) The reflected light from the disk irradiated onto the photodetector 111 is converted into a current by the four-divided photodetector 111, and is input to the I / V converters 114, 115, 119, and 120. The I / V converters 114, 115, 119, and 120 convert the input current into a voltage according to the current level. The adders 121, 122, 123, and 124 add the two input signals from the four I / V converters 114, 115, 119, and 120, respectively, and output two outputs from each of the two differential amplifiers 125, Send to 117. The differential amplifier 117 calculates the difference between the two input voltages that are the outputs of the adders 123 and 124, and outputs the calculated value.

The optical system shown in FIG. 1 constitutes a focusing error detection method generally called an astigmatism method. Therefore, the output of the differential amplifier 117 becomes a focusing error signal (hereinafter, referred to as an FE signal) indicating a deviation between the focal point of the light beam 150 and the information surface of the disk 100. The FE signal is sent to the power amplification circuit 133 via the phase compensation circuit 130, the switch 131, and the adder 132, and the power amplification circuit 133 applies a voltage to a focusing coil (not shown) of the actuator 112. . As described above, the phase compensation circuit 130 stabilizes the focusing control system. By driving the focusing lens 110 according to the FE signal, or when switching to the focusing lens 126, the focusing lens 126 is By driving, the focal point of the light beam is always positioned on the information surface.

The differential amplifier 125 calculates the difference between the two input voltages that are the outputs of the adders 121 and 122, and outputs the calculated value. The optical system shown in FIG. 1 constitutes a tracking error detection method generally called a push-pull method. Accordingly, the output of the differential amplifier 125 becomes a tracking error signal (hereinafter, referred to as a TE signal) indicating a deviation between the focal point of the light beam 150 and the track of the disk 100. The TE signal is sent to the power amplifier 136 via the switch 134 and the phase compensation circuit 135, and the output of the power amplifier 136 is applied as a voltage to the tracking coil (not shown) of the actuator 112. As described above, the phase compensation circuit 135 stabilizes the tracking control system. When the focusing lens 110 is driven in accordance with the TE signal, or when the focusing lens is switched to 126, the focusing lens 126 is used. Is driven so that the focal point of the light beam is always positioned on the track.

The output of the adder 148 is a signal obtained by adding the outputs of all the photodetectors 111, and indicates the total amount of reflected light from the disk. Hereinafter, this output signal is referred to as an AS1 signal, which is a signal that changes according to the presence or absence of a pit on a disk. The AS1 signal indicating the total reflected light amount is sent to an envelope detection circuit 143 and a signal processing circuit (not shown) for demodulating information.

The envelope detection circuit 143 outputs a signal level of an AC component generated by a pit on the disk, and this output signal is hereinafter referred to as an ENV signal.

The low-pass filter 165 (hereinafter, referred to as LPF) removes an AC component generated by a pit on the disk from the AS1 signal, and the AS1 signal passed through the LPF 165 is hereinafter referred to as an AS1L signal. The AS1L signal, the ENV signal, and the FE signal are converted into digital signals by analog / digital converters 142, 144, and 140 (hereinafter, referred to as A / D converters) and sent to the microcomputer 147.

Next, the operation of the optical disk device according to the first embodiment will be described.
When the disk 100 is placed on the tray 149, the microcomputer 147 drives the motor 118 to attach the disk 100 to the rotating shaft 102 of the motor 101.

Next, the microcomputer 147 sets a predetermined value in the digital / analog converter 145, moves the transfer table 104 to the inner periphery of the disk 100 by the transfer motor 103 via the power amplifier circuit 139, and sets the motor 128 By driving, the focusing lens and the actuator are switched to the focusing lens 110 and the actuator 112 for DVD.

(4) Further, the microcomputer 147 rotates the motor 101. The rotation speed of the motor is a rotation speed specified when reproducing information on the inner circumference of the DVD. When the number of revolutions of the motor 101 reaches the set number, the motor 101 sends an OK signal to the terminal a of the microcomputer 147. When the OK signal is sent, the microcomputer 147 sends the laser drive circuit 129 via the terminal b. To make the laser emit a state of emitting light. The microcomputer 147 sets the radiation intensity in the laser drive circuit 129 via the D / A converter 146. The radiation intensity of this laser is set to a low value so that even if a CD-R disc is loaded in the present optical disc apparatus, information on the CD-R disc is not destroyed.

Further, the microcomputer 147 sets a value in the D / A converter 141, and once lowers the focusing lens 110 via the adder 132 and the power amplifier circuit 133 and then gradually raises it, that is, moves the focusing lens 110 away from the disk 100. Later, gradually approach. At this time, the switches 131 and 134 are kept open so that the focusing coil and the tracking coil of the actuator 112 are not driven in response to the FE signal and the TE signal. I do. The microcomputer 147 converts the FE signal, the AS1L signal, and the ENV signal into the A / D converter 140, the LPF 165, the A / D converter 142, and the A / D converter while the focusing lens 110 is moving. The microcomputer 147 determines whether the disk 100 loaded in the optical disk device is a single-layer DVD or a double-layer DVD based on the FE signal, AS1L signal, and ENV signal. , CD, or CD-R.

After performing the above determination, if the loaded disc is a CD-R, the information recorded on the disc 100 may be destroyed. 149, and ejects the disc 100 from the apparatus. If the loaded disk is a CD, the microcomputer 147 drives the motor 128 to switch the actuator and the focusing lens to the actuator 127 and the focusing lens 126 for the CD.

Next, the microcomputer 147 controls the laser drive circuit 129 to determine the radiation intensity of the laser 105 according to whether the loaded disk is a CD or a DVD as a result of the above-described determination. , Or DVD. Then, the output value of the D / A converter 141 is set to zero, the switches 131 and 134 are closed through the adder 132, and the actuator 112 is connected to the output of the power amplifier circuits 133 and 136 by the loops formed by the switches. To perform focusing control and tracking control, thereby reproducing information recorded on the disc 100.

The disc determination by the microcomputer 147 is performed only when the disc 100 is newly mounted on the rotating shaft 102 of the motor 101. Therefore, for example, when the reproduction of the information on the disk is temporarily stopped and then the reproduction is restarted, the disc is not determined. Therefore, this makes it possible to shorten the rise time when the reproduction is restarted.

Next, the FE signal, the AS1L signal, and the ENV signal will be described.
FIGS. 2A to 2E show waveform diagrams of signals when the focusing lens 110 is gradually raised from a lowered state when a single-layer DVD (DVD1) is loaded in the optical disk apparatus. . 2A to 2E, the vertical axis indicates the signal level and the horizontal axis indicates the time. FIG. 2A shows the FE signal, FIG. 2B shows the AS1 signal, and FIG. 2C shows the AS1L signal, FIG. 2D shows the ENV signal, and FIG. 2E shows the position of the focal point F. Each of the FE signal, AS1 signal, AS1L signal, and ENV signal changes when the focal point of the light beam applied to the disk passes through the information recording surface, that is, the aluminum reflective film. , The FE signal becomes zero at time t1 when the position of the focal point of the light beam coincides with the information surface of the disk. Here, the waveform of the FE signal when the focal point of the light beam passes through the information surface of the disk is generally called an S-shaped curve. The AS1 signal gradually increases as the focal point of the light beam approaches the information surface of the disk, and gradually decreases as the focal point of the light beam moves away. This changes depending on the presence or absence of pits on the disk. The AS1L signal is a signal obtained by averaging the level change of the AS1 signal due to pits on the disk. The ENV signal is a signal indicating a level change of the amount of reflected light depending on the presence or absence of a pit on the disk. The position of the focal point F of the light beam shown in the waveform of FIG. 2E is determined by the signal level output from the microcomputer 147 to the D / A converter 141.

Here, the microcomputer 147 moves the position of the focal point F of the light beam late from time t0 to time t2 as shown in the waveform of FIG. The reason for this is that the slower the movement, the more slowly the signal level changes, and the more accurate the measurement of the FE signal, AS1L signal, and ENV signal. Note that a period between time t0 and time t2 is a period during which the AS1L signal exceeds the reference value W. The reason why the AS1L signal exceeds the reference value W during this period is that the focal point of the light beam is near the information surface of the disk during this period. Therefore, during the period from time t0 to time t2, the position of the focal point F of the light beam is moved slowly so that each signal can be accurately measured and the time for discriminating the disk can be shortened. .

Next, a description will be given of a disk discrimination method performed by the microcomputer 147 based on the detection result of the FE signal, the AS1L signal, and the ENV signal.

(4) The microcomputer 147 calculates the maximum values of the FE signal, the AS1L signal, and the ENV signal.

FIGS. 3A to 3D show the ENV signal and the AS1L signal when the focusing lens 110 is gradually raised. 3A to 3D, the vertical axis represents the signal level and the horizontal axis represents the time. FIG. 3A shows the case of a single-layer DVD (referred to as DVD1). FIG. 3B shows the case of a double-layer DVD (referred to as DVD2), FIG. 3C shows the case of a CD, and FIG. 3D shows the case of a CD-R.

In the waveform of FIG. 3A, Kenv and Kas are the maximum values of the ENV signal and the AS1L signal during the period when the focusing lens 110 is moved, and are shown in FIGS. 3B, 3C, and 3C. The same applies to Lenv, Las, Menv, Mas, Nenv, and Nas in (d).

(4) The levels of the ENV signal and the AS1L signal are maximum in a single-layer DVD (DVD1) and minimum in a CD-R. The levels Lenv and Las of the ENV signal and AS1L signal of the dual-layer DVD (DVD2) are lower than those (Kenv, Kas) of the single-layer DVD (DVD1) in the dual-layer DVD (DVD2). This is because the reflectivity of the first layer, about 35%, is lower than the reflectivity of the single-layer DVD (DVD1), about 90%.

The reason why the level ENv of the CD ENV signal is lower than those of the DVDs (DVD1, DVD2) (Kenv, Lenv) is to measure the CD ENV signal using a DVD optical system. .

Further, there is a difference between the ENV signal and the AS1L signal (Menv and Nenv, and Mas and Nas) between the CD and the CD-R because the absorptance of the CD-R at 650 nm is larger than that of the CD.

In the waveform of FIG. 3A, Kenv and Kas are the maximum values of the ENV signal and the AS1L signal during the period when the focusing lens 110 is moved, and are shown in FIGS. 3B, 3C, and 3C. The same applies to Lenv, Las, Menv, Mas, and Nenv, Nas in (d).

After calculating the maximum values of the FE signal, the AS1L signal, and the ENV signal, the microcomputer 147 previously stores Pas satisfying the relationships of Nas <Pas <Mas, Nas <Pas <Las, and Nas <Pas <Kas. The Pas is compared with the maximum value of the AS1L signal, and when the maximum value of the AS1L signal is equal to or smaller than Pas, the loaded disc is determined as a CD-R. If the disc is a CD-R, the motor 118 is driven to move the tray 149, and the disc 100 is ejected from the apparatus.

Next, the microcomputer 147 calculates Kenv / Kas, Lenv / Las, Menv / Mas, and Nenv / Nas. Here, the reason why the maximum value of the ENV signal is divided by the maximum value of the AS1L signal is to absorb the influence of variations in the reflectance of the disk 100 and the radiation intensity of the laser 105 with respect to the maximum value of the ENV signal.

According to an experiment, this value is about 6 for a single-layer DVD (DVD1) and a double-layer DVD (DVD2), and is about 2 for a CD. Accordingly, the microcomputer 147 determines that the disk is a DVD when the above value is 4 or more, and determines that the disk is a CD when the above value is 4 or less. However, if the amplification rate of the ASL signal is different from the amplification rate of the ENV signal, the result of the division will be different. In this case, the comparison value is changed according to the amplification rate.

If the disc loaded in the present optical disc apparatus is a CD, the microcomputer 147 drives the motor 128 to switch the actuator and the focusing lens to the actuator 127 and the focusing lens 126 for the CD.

When the disc loaded in the optical disc apparatus is a DVD, the microcomputer 147 stores in advance a Qenv satisfying the relationship of Lenv <Qenv <Kenv, and compares the value of the Qenv with the measured ENV signal. Based on the result, it is determined whether the DVD is a single-layer DVD (DVD1) or a double-layer DVD (DVD2).

In the first embodiment, the discrimination between the single-layer DVD (DVD1) and the double-layer DVD (DVD2) is performed using the maximum value of the ENV signal. It can also be performed using the value or the maximum value of the AS1L signal. This is for the same reason that a difference occurs in the level of the ENV signal, that is, due to the difference in reflectivity between the single-layer DVD and the double-layer DVD, and to the level of the amplitude of the FE signal or the level of the AS1L signal. This is because a difference occurs.

In the first embodiment, the CD-R is determined based on the level of the AS1L signal. However, the determination can be performed based on the level of the FE signal or the level of the ENV signal. This is because the level of the FE signal or ENV signal of the CD-R is lower than that of the CD in the same reason as in the case of the AS1L signal, that is, because the CD and the CD-R have different absorption rates. .

In the first embodiment, the discrimination between a CD and a DVD is made based on the value obtained by dividing the maximum value of the ENV signal by the maximum value of the AS1L signal. Is larger than the maximum value of the ENV signal of the CD which is to be detected by the lens for CD and detected by the lens for DVD. Therefore, based on the maximum value of the ENV signal itself, the single-layer DVD and the double-layer DVD are used. , CD, and CD-R, the detection output of the DVD and the CD is determined by the fact that the optimal detection lens is not used for the substrate thickness due to the difference in reflectance between the single-layer DVD and the double-layer DVD. The discrimination can be made based on the difference and the difference between the CD and the CD-R in the absorbance.

{Circle around (4)} When the determination is made based on the maximum value of the ENV signal, the division is not performed, so that the processing by the microcomputer 147 can be easily performed.

In the first embodiment, the emission intensity of the laser 105 is reduced to determine whether or not the disc is a CD-R. However, the first movement of the focusing lens 110 in the vertical direction with respect to the disc causes the CD to be discarded. After confirming that the value is not -R, the radiation intensity of the laser 105 may be increased, and the focusing lens 110 may be moved a second time in the vertical direction with respect to the disk to determine the DVD or the CD. In this case, by increasing the radiation intensity of the laser, the level of the detection signal can be made higher than that of the noise, so that the accuracy of determination can be greatly improved.

In the first embodiment, disc discrimination is performed using an optical system for DVD, but this may be performed using an optical system for CD. However, in this case, since the magnitude relationship between the ENV signal and the FE signal is reversed, it is necessary to change the determination condition.

In the first embodiment, the focusing lens 110 is once moved away from the disc 100 and then gradually approached to measure the FE signal, ENV signal, and AS1L signal at that time. May be measured when moving away from the above, and the same result as above can be obtained.

As described above, according to the optical disc device of the first embodiment, the maximum value of the AS1L signal and the ENV signal is measured, and the value obtained by dividing the maximum value of the ENV signal by the maximum value of the AS1L signal is determined in advance. Since the configuration is made so as to be compared with the set reference value, it is possible to discriminate between a DVD having a small base material and a CD having a large base material.

Also, since the maximum value of the AS1L signal itself is compared with a predetermined reference value, a CD-R disc can be identified with a simple configuration.

Further, since the disc is determined by setting the intensity of the light beam to be lower than the intensity at the time of reproducing the information of the disc, even if the loaded disc is a CD-R, the disc cannot be discriminated when the disc is discriminated. No information is destroyed.

Also, since the maximum value of the ENV signal amplitude is compared with a predetermined reference value, the simplest configuration allows the maximum value of the ENV signal to be less than or equal to a predetermined level. It can be distinguished from a dual-layer DVD.

In addition, since the maximum value of the ENV signal amplitude is measured and the result is compared with a predetermined reference value, a DVD having a thin base material and a CD having a thick base material can be used with a simple structure. Can be determined.

In addition, since discs are identified using the optical system for disks with thin base materials, the time it takes for disc information to be reproduced when a disk with thin base materials is loaded is reduced. Is done.

Further, since the moving speed of the focusing lens 110 is reduced when the level of the AS1L signal becomes equal to or more than the reference value W, the level change of the AS1L signal, the ENV signal, and the FE signal becomes gentle, and accordingly, the microcomputer 147 An accurate maximum value of the amplitude of the AS1L, ENV signal, and FE signal can be obtained, and the reliability of disc discrimination can be improved.

In the first embodiment, CD-R discrimination is performed using the maximum value of the AS1L signal. However, the discrimination may be performed using the maximum value of the amplitude of the FE signal. This is because the level of the amplitude of the FE signal of the CD-R is lower than the level of the amplitude of the FE signal of the CD for the same reason that the level of the AS1L signal of the CD-R is lower than the level of the AS1L signal of the CD. Because. Therefore, also in this case, the same effect as when the AS1L signal is used can be obtained.

In addition, the discrimination between the single-layer DVD and the double-layer DVD is performed using the maximum value of the ENV signal, but this is performed using the maximum value of the amplitude of the FE signal or the maximum value of the AS1L signal. You can also. This is because there is a difference in the maximum value of the AS1L signal between the single-layer DVD and the double-layer DVD for the same reason as the difference in the amplitude level of the ENV signal. Therefore, also in this case, the same effect as when the ENV signal is used can be obtained.

Embodiment 2 FIG.
Hereinafter, a second embodiment of the present invention will be described.
FIG. 4 shows a block diagram of an optical disk device according to Embodiment 2 of the present invention. 4, the same reference numerals as those in the first embodiment denote the same parts. In the second embodiment, discrimination between DVD and CD is performed (however, discrimination between single-layer DVD and double-layer DVD cannot be made).

In the optical disk device according to the second embodiment, a band-pass filter 160 and a comparator 161 are newly added to the configuration of the optical disk device according to the first embodiment. The band pass filter 160 allows only a signal of a predetermined frequency to pass. The comparator 161 outputs a high-level signal when the level of the input signal exceeds a predetermined value. Therefore, it can be determined whether or not the signal of the pass band of the band-pass filter 160 is recorded on the disk 100 based on whether or not the output value of the comparator 161 has become high level. Here, the pass band of the band-pass filter 160 is set near 4 MHz.

Next, the operation of the optical disk device according to the second embodiment will be described.
As in the first embodiment, when the disk 100 is placed on the tray 149, the microcomputer 147 drives the motor 118 to attach the disk 100 to the rotating shaft 102 of the motor 101.

Next, the microcomputer 147 sets a predetermined value in the D / A converter 145, moves the transfer table 104 to the inner periphery of the disk 100 by the transfer motor 103 via the power amplifier circuit 139, and sets the motor 128 By driving, the focusing lens and the actuator are switched to the focusing lens 110 and the actuator 112 for DVD. Then, the microcomputer 147 rotates the motor 101. Here, the rotation speed of the motor is a rotation speed specified when reproducing information on the inner circumference of the DVD. Further, the microcomputer 147 sets a value in the D / A converter 141 and moves the focusing lens 110 away from the disk 100 once and then gradually. At this time, the switches 131 and 134 are kept open so that the focusing coil and the tracking coil of the actuator 112 are not driven according to the FE signal and the TE signal.

The above is the same as in the first embodiment.
Next, a disc determination method according to the second embodiment will be described.

(4) The highest frequency of the signal recorded on the DVD is about 4 MHz, and the linear velocity of the DVD is about 3.3 m / s. In the case of a CD, the linear velocity is about 1.3 m / s, and the maximum frequency of the signal reproduced at this time is about 700 KHz. Therefore, the maximum frequency when the CD is rotated at the linear velocity of the DVD is 700 KHz × (3.27 / 1.3) = 1.8 MHz. Therefore, if the output of the comparator 161 becomes high level when the focusing lens is moved, it is known that the detection signal includes a signal component of 4 MHz, and the mounted disk is a DVD. The operation after discrimination of the disc is the same as that in the first embodiment.

In the above-described example of the second embodiment, the band-pass filter 160 that passes a 4 MHz signal component is used, and its output is detected by the comparator 161 to detect whether or not there is a 4 MHz signal component. The disc is discriminated whether the disc is a DVD or a CD. This is done by binarizing the input signal of the band-pass filter 160 and measuring the period of the high level or the low level to obtain a 4 MHz signal. Whether or not there is a signal component may be detected. Here, in the case of a DVD, the period of the high level or the low level is about 125 ns.

FIG. 5 shows a block diagram of an example having such a configuration. 4 is different from the block diagram of FIG. 4 in that a high-pass filter 700 (hereinafter, referred to as HPF 700) having an AS1 signal output from the adder 148 as an input, a comparator 701 having the output as an input, and a cycle having the output as an input. A measurement circuit 702 and a microcomputer 747 to which the output is input. The HPF 700 is a filter that passes only high frequency components of an input signal. The cutoff frequency of the HFP 700 is set to a frequency at which a frequency component of information recorded on the disc 100 passes. Therefore, the signal component of the information recorded on the disc 100 is input to the comparator 701. The comparator 701 is a binarizing circuit that converts an input signal into a high level or a low level based on a zero level. Therefore, the output of the comparator 701 is a signal obtained by binarizing the signal component of the information recorded on the disk 100. The period measurement circuit 702 measures the time of the high level and the low level of the input signal, and sends the measured value to the microcomputer 747. When the microcomputer 747 receives a measurement value near 125 ns from the period measurement circuit 702, the microcomputer 747 determines that the currently loaded disk is a DVD. This is because a measured value of 125 ns corresponds to a signal component of 4 MHz. The operation of the microcomputer 747 is the same as the operation of the microcomputer 147 except that the microcomputer 747 takes in the measured values and discriminates the disk.

As described above, according to the optical disk device of the second embodiment, the bandpass filter 160 shown in FIG. 4 determines whether or not the AS1 signal corresponding to the amount of reflected light from the disk contains a signal of a predetermined frequency component. , And the comparator 161, it is possible to discriminate between a DVD having a high linear recording density and a CD having a low linear recording density.

In addition, the high-pass filter 700, the comparator 701, and the period measurement circuit 702 shown in FIG. 5 can similarly detect whether the AS1 signal corresponding to the amount of reflected light from the disk contains a signal of a predetermined frequency component. Therefore, it is possible to distinguish between a DVD having a high linear recording density and a CD having a low linear recording density.

Embodiment 3 FIG.
Hereinafter, a third embodiment of the present invention will be described.

FIG. 6 is a block diagram showing the configuration of the optical disk device according to the third embodiment. The same reference numerals as those in the first embodiment denote the same parts. The device according to the third embodiment is different from the device according to the first embodiment in that the actuators 112 and 127 and the focusing lenses 110 and 126 are replaced with the actuator 172, the focusing lens 170, and the hologram 171. is there.

This optical system will be described with reference to the schematic diagram of FIG. The hologram 171 is formed only near the center of the optical axis of the light beam 150, and the light beam 150 that has passed through the focusing lens 170 connects the focal point FCD for CD and the focal point FDVD for DVD. The focus FCD for CD is located farther from the focusing lens 170 than the focus FDVD for DVD. The distance between the focus FCD for CD and the focus FDVD for DVD is about 300 μm. The intensity of the focal point is about twice as high for the DVD focal point FDVD as for the CD focal point FCD.

6, in the same manner as in the first embodiment, when the disc 100 is placed on the tray 149, the microcomputer 147 drives the motor 118 to attach the disc 100 to the rotating shaft 102 of the motor 101. Next, the transfer table 104 is moved to the inner periphery of the disk 100 by the transfer motor 103 via the power amplification circuit 139. Then, the microcomputer 147 rotates the motor 101. The rotation speed of the motor is a rotation speed specified when reproducing information on the inner circumference of the DVD. When the number of revolutions of the motor 101 reaches the set number, the motor 101 sends an OK signal to the terminal a of the microcomputer 147. When the OK signal is sent, the microcomputer 147 sets a value in the D / A converter 141. The focusing lens 170 is once lowered and then gradually raised. At this time, the switches 131 and 134 are open.

{Circle around (4)} After the focusing lens 170 moves to the upper limit, the microcomputer 147 determines the disc. If it is determined that the disc is a CD-R, the motor 118 is driven to move the tray 149 and eject the disc 100 from the apparatus. When the disc is a CD, the focusing lens 170 is lowered again and then gradually raised to close the switch 131 at the timing when the ENV signal exceeds a predetermined level and the FE signal first crosses zero, thereby performing the focusing control. .

If the disc is a DVD, the switch 131 is closed at the timing when the FE first crosses zero while the focusing lens 170 is gradually lowered from the disc 100, and the focusing control is operated.

The reason why the moving direction of the focusing lens 170 is changed between CD and DVD when the focusing control is operated will be described in detail below.

FIG. 8 shows the FE signal and the ENV signal when the focusing lens 170 is once lowered and then gradually raised. The horizontal axis indicates time. In the case of an optical system having two focal points, the FE signal and the ENV signal change depending on the focal point FCD for CD and the focal point FDVD for DVD.

In the case of the single-layer DVD shown in FIG. 8A and the dual-layer DVD shown in FIG. 8B, both the FE signal and the ENV signal change at the first CD focus FCD (left side in the figure), Thereafter, the FE signal and the ENV signal change at the DVD focus FDVD (right side in the figure). This is because the CD focal point FCD is located farther from the focusing lens 170 than the DVD focal point FDVD. Therefore, in the case of a DVD, the focusing lens 170 is once raised and then gradually lowered while first or second (in the case of a single-layer DVD and a double-layer DVD, respectively) when the FE signal crosses zero (time t12 or time t12). At t13), the focusing control system is operated. In the case of a CD, the focusing control system is operated at the first timing (time t11) when the ENV signal exceeds a predetermined level and the FE signal crosses zero while gradually lowering and then gradually raising the focusing lens 170. The condition of the ENV signal is that the waveform (time t10) indicated by the dotted line in the FE signal in the case of the CD in FIG.

Next, a method for discriminating a disk performed by the microcomputer 147 will be described.
The microcomputer 147 captures the FE signal, the AS1L signal, and the ENV signal while the focusing lens 170 is being gradually raised, and measures the maximum value.

FIG. 9 shows the ENV signal and the AS1L signal when the focusing lens 170 is gradually raised. The vertical axis indicates the signal level, and the horizontal axis indicates time.

9 (a) shows a single-layer DVD, FIG. 9 (b) shows a two-layer DVD, FIG. 9 (c) shows a CD, and FIG. 9 (d) shows a CD-R.

In the waveform of FIG. 9A, Senv indicates the maximum value of the ENV signal during the period when the focusing lens 170 is moved. Sas similarly indicates the maximum value of the AS1L signal.
The same applies to the waveforms of FIGS. 9 (b), (c) and (d).

The signal levels of the ENV signal and the AS1L signal become high when the focal point FCD for CD and the focal point FDVD for DVD coincide with the information surface, respectively. The maximum value of the ENV signal is maximum for a single-layer DVD (Senv), almost equal for a double-layer DVD and a CD (Tenv, Uenv), and minimized for a CD-R (Venv). In addition, the maximum value of the AS1L signal is large and almost equal to that of the single-layer DVD (Sas) and that of the CD (Uas), and the maximum value (Tas) of the AS1L signal of the double-layer DVD is smaller than that of the CD (Uas). CD-R (Vas) is minimized.

The maximum value (Tenv, Tas) of the ENV signal and AS1L signal of the dual-layer DVD is lower than that of the single-layer DVD (Senv, Sas) because the reflectivity of the first layer of the dual-layer DVD is one. This is because the reflectance is lower than that of the expression DVD.

The reason why the level (Uenv) of the ENV signal due to the CD focus FCD in the CD is lower than that of the single-layer DVD (Senv) is that the light quantity of the CD focus FCD is about 50% of that of the DVD focus FDVD. . Also, the level (Uenv) of the ENV signal by the DVD focus FDVD in the CD is lower than the level of the ENV signal (Senv) by the DVD focus FDVD in the single-layer DVD, because the DVD focus FDVD is 0.6 mm. This is because the focus is blurred because it is designed based on the thickness of the base material.

The difference between the ENV signal and the AS1L signal between the CD and the CD-R (the difference between Uenv and Venv, the difference between Uas and Vas) is because the absorptance of the CD-R at 650 nm is larger than that of the CD.

The microcomputer 147 that has measured the maximum values of the FE signal, the AS1L signal, and the ENV signal previously stores Was that satisfies the relationships Vas <Was <Uas, Vas <Was <Tas, and Vas <Was <Sas. The maximum value of the AS1L signal is compared with Was, and when the maximum value is equal to or less than Was, the filled disc is determined as a CD-R. If it is determined that the disc is a CD-R, the motor 118 is driven to move the tray 149, and the disc 100 is ejected from the apparatus.

(4) The microcomputer 147 calculates Senv / Sas, Tenv / Tas, and Uenv / Uas. Senv / Sas and Tenv / Tas are almost equal. Uenv / Uas is smaller than Senv / Sas and Tenv / Tas.

The microcomputer 147 stores a predetermined value Z in advance, and compares the value Z obtained by dividing the maximum value of the ENV signal by the maximum value of the AS1L signal with the above value Z to determine whether the loaded disk is a DVD or a CD. Is determined.

Next, the value Z will be described.
As the value Z, Senv / Sas, Tenv / Tas, and Uenv / Uas are measured in advance on a standard disc, and the value Z is determined based on the result. In an apparatus in which the intensity of the DVD focus FDVD is set to about twice the intensity of the CD focus FCD, the value of Z is about 6 for a single-layer DVD and a double-layer DVD, and 2 for a CD. About. Therefore, the value Z is a value between 2 and 6. The value Z is 6 / Z = Z / 2 so that the disk can be accurately identified even if the characteristics of the disk vary.
Set a value that satisfies. The value of Z is about 4. FIG. 23 shows the relationship between the value Z and the disk type in the third embodiment. If the value obtained by dividing the maximum value of the ENV signal by the maximum value of the AS1L signal is greater than 4, it is determined to be a DVD; However, since the result of the division differs depending on the difference between the amplification factors of the ENV signal and the AS1L signal, when the amplification factor is changed, the value Z needs to be changed accordingly.

If the intensity ratio between the DVD focus FDVD and the CD focus FCD is changed, it is necessary to change the comparison value in accordance with the intensity ratio.

As described above, according to the optical disc device of the third embodiment, the maximum value of the AS1L signal and the ENV signal is measured, the maximum value of the ENV signal is divided by the maximum value of the AS1L signal, and the result is determined in advance. An optical disk using an optical head having two focal points, one for reproducing a disk with a thick base material and the other for reproducing a disk with a thin base material, because it is configured to be compared with a reference value set in advance. Even with an apparatus, it is possible to distinguish between a DVD having a small base material and a CD having a large base material.

When the microcomputer 147 determines that the loaded disk is a CD having a large base material, the microcomputer 147 sets the D / A converter 141 to a predetermined value to move the focusing lens 170 closer to the disk 100. When the microcomputer 147 detects the timing for operating the focusing control, the microcomputer 147 closes the switch 131 to operate the focusing control. Therefore, even in an optical disk apparatus using an optical head having two focal points, one for reproducing a disk with a thick base material and the other for reproducing a disk with a thin base material, a CD having a thick base material can be used. , The focusing control can be operated normally.

When the microcomputer 147 determines that the loaded disk is a DVD having a thin base material, the microcomputer 147 sets the D / A converter 141 to a predetermined value to move the focusing lens 170 away from the disk 100. . When the microcomputer 147 detects the timing for operating the focusing control, the microcomputer 147 closes the switch 131 to operate the focusing control. Therefore, even in an optical disc apparatus using an optical head having two focal points, one for reproducing a disk with a thick base material and the other for reproducing a disk with a thin base material, regardless of the base material thickness, Focusing control can be operated normally.

Embodiment 4 FIG.
Hereinafter, Embodiment 4 of the present invention will be described.
FIG. 10 shows a block diagram of an optical disk device according to the fourth embodiment. The same blocks as those in the third embodiment are denoted by the same reference numerals, and description thereof is omitted. The differences from the third embodiment are that a photodetector 411, a microcomputer 447, an I / V converter 450, a low-pass filter 451, A / D converters 452 and 461, an amplifier 453 having a variable amplification factor, and adders 454 and 462. , D / A converter 455.

The photodetector 411 is a photodetector whose light-receiving surface is divided into five, and has a configuration in which one light-receiving surface is added to the photodetector 111 in the third embodiment. FIG. 11 shows the configuration of the photodetector 411. That is, the photodetector 111 according to the third embodiment includes four light receiving surfaces A, B, C, and D, whereas the photodetector 411 according to the fourth embodiment includes: It has five light receiving surfaces A, B, C, D, and E. The light receiving surface E is added to the photodetector 111. The light receiving surfaces A, B, C, and D constitute an inner part of the photodetector 411, and one side of the inner part is about 200 μm. The light receiving surface E forms an outer portion of the photodetector 411, and one side of the outer portion is about 2 mm.

Here, the output of the adder 148 indicating the value obtained by adding the output signals of the light receiving surfaces A, B, C, and D is referred to as an AS1 signal. Therefore, as in the first, second, and third embodiments, the output of the differential amplifier 117 shown in FIG. 10 becomes an FE signal indicating a shift between the focal point of the light beam 150 and the information surface of the disk. Further, the output of the differential amplifier 125 becomes a TE signal indicating the deviation between the focus point of the light beam 150 and the track. The output of the added light receiving surface (E) is sent to the I / V converter 450. The output of I / V converter 450 is sent to addition circuit 462 and LPF 460. The output signal of the adder 462 is a signal obtained by adding the output signals of all the light receiving surfaces of the photodetector 411, and this signal is hereinafter referred to as an AS signal. Similarly, the output signal of the LPF 451 is called an ASL signal, the output signal of the I / V converter 450 is called an AS2 signal, and the output signal of the LPF 460 is called an AS2L signal. The ASL signal is sent to the A / D converter 461. The microcomputer 447 captures the output signal of the A / D converter 461, and similarly, the microcomputer 447 captures the AS2L signal via the A / D converter 452. I / V converter 450 operates similarly to I / V converter 120. Similarly, the LPFs 451 and 460 and the A / D converters 461 and 452 operate similarly to the LPF 165 and the A / D converter 142, respectively. The amplifier 453 is an amplifier that changes the amplification factor according to a command from the microcomputer 447. The adder 454 and the D / A converter 455 operate similarly to the adder 132 and the D / A converter 141, respectively.

The operation of the device shown in FIG. 10 will be described with reference to the flowchart shown in FIG.
In FIG. 10, as in Embodiment 3, when the disc 100 is placed on the tray 149, the microcomputer 447 drives the motor 118 to attach the disc 100 to the rotating shaft 102 of the motor 101 (step S1).

Next, the microcomputer 447 drives the transfer motor 103 by the D / A converter 145 and the power amplifier circuit 139 to move the transfer table 104 in the inner circumferential direction of the disk 100 (step S2). Then, the microcomputer 447 rotates the motor 101. The number of revolutions is the number of revolutions specified when reproducing information on the inner circumference of the DVD (step S3).

(4) In this state, the microcomputer 447 determines whether the disk 100 is a DVD, a CD, or a CD-R (step S4). The method of disc determination will be described later.

Here, the above-described discrimination method is configured such that the position of the focusing lens 170 at the time when the discrimination processing is completed is closer to the disc 100 than the position where the focusing control is operating normally. ing.

The operation when the disc 100 is a DVD will be described below.
The microcomputer 447 sets the amplification factor of the amplifier 453 based on the value AS1Lp (p means “peak”) measured in the determination process (step S5). Next, while the focusing lens 170 is gradually lowered by the D / A converter 141 via the adder 132 and the power amplifier circuit 133, the FE signal detected at that time is amplified by the amplifier 453, and the A / D converter Based on the output value obtained by the A / D conversion in 140, the timing at which the FE signal first crosses zero is detected (step S6). When the zero-cross timing is detected, the output value of the D / A converter 141 is set to zero, the switch 131 is closed, and the focusing control is operated (step S6). The above AS1Lp will be described later.

The operation when the disc 100 is a CD will be described below.
The microcomputer 447 sets the amplification factor of the amplifier 453 based on the value AS1Lp measured in the determination process, as in the case of the DVD (step S7). Further, the number of rotations of the motor 101 is set to the number of rotations when reproducing the inner circumference of the CD.

Next, after the focusing lens 170 is once lowered (Step S8), the FE signal is first zero-crossed based on the output value of the A / D converter 140 while gradually raising it, and the envelope detection circuit 143 The first timing when the output ENV signal exceeds a predetermined level is detected (step S9). When the zero-cross timing is detected, the output value of the D / A converter 141 is set to zero, and the switch 131 is closed to operate the focusing control (step S9).

The reason why the moving direction of the focusing lens 170 is changed between a CD and a DVD is as described above. Therefore, when a DVD is loaded in the apparatus, the operation of once lowering the focusing lens 170 is not necessary, and thus, signal reproduction can be started in a shorter time than when a CD is loaded. Therefore, when a DVD is loaded more frequently than a CD, on average, there is an advantage that signal reproduction can be started in a short time.

If the disc is a CD-R, drive the motor 118 to move the tray 149 and eject the disc 100 (step S10).

Next, a method of discriminating the disk performed by the microcomputer 447, which will be described later, will be described.

In FIG. 13, the value of the FE signal, ENV signal, AS1L signal, ASL signal, and ENV / ASL obtained by dividing the level of the ENV signal by the level of the AS1L signal when the focusing lens 170 is once lowered and then gradually raised. Is shown. The vertical axis indicates the signal level, and the horizontal axis indicates time.

13 (a) shows the case of a single-layer DVD, FIG. 13 (b) shows the case of a two-layer DVD, and FIG. 13 (c) shows the case of a CD.

The signals of the ENV signal and the AS1L signal change depending on the focus FCD for CD and the focus FDVD for DVD. Further, in the FE signal, when each of the focal points FCD and FDVD passes through the information surface, a level change generally called an S-shaped curve occurs.

According to the experiment, the state where the value of ENV / ASL becomes the maximum is the state where the DVD focus FDVD coincides with the information surface in the case of DVD. The reason will be described. Since the ASL signal is a low-frequency component of the amount of reflected light, ENV / ASL indicates the rate at which the light beam applied to the disk is modulated by the pits on the disk. Therefore, the state where the focal point suitable for the loaded disk is located on the information surface of the disk is a state where the information of the disk is efficiently reproduced. In the case of DVD, the DVD focus FDVD matches the information surface. In this state, ENV / ASL becomes maximum. In the single-layer DVD, ENV / ASL becomes maximum at time t31 of the waveform in FIG. In the dual-layer DVD, the values of ENV / ASL are almost equal and maximum at times t32 and t33 of the waveform in FIG. In the case of a CD, ENV / ASL becomes the maximum value at time t30 of the waveform shown in FIG.

In the fourth embodiment, the ENV signal is obtained from the light intensity ASL received by all the light receiving surfaces A, B, C, D, and E of the photodetector 411. Similar results can be obtained by obtaining the light intensity AS1L received by C and D. Although the value of ENV is divided by the value of ASL, AS1L may be used instead of ASL, and the same result is obtained.

In such a situation, in a state where ENV / ASL becomes the maximum value, the value of AS1L / AS2L obtained by dividing the level of AS1L by the level of AS2L which is a waveform obtained by subtracting the level of AS1L from the level of ASL is 1 The value of the layered DVD is larger than the value of the dual layer DVD and the value of the CD. That is, in the single-layer DVD, the intensity of the light beam at the center of the photodetector 411 is high.

Hereinafter, the reason will be described with reference to FIG.
FIG. 24 shows a state in which ENV / ASL is maximum when the disc 100 is a single-layer DVD, a double-layer DVD, or a CD in the fourth embodiment. FIG. 24A shows the positional relationship between the DVD focus FDVD and the CD focus FCD and the information surface, and FIG. 24B shows the reflected beam from the information surface of the disc 100 to the photodetector 411.

First, the case of a single-layer DVD will be described. In the case of a single-layer DVD, the ENV / ASL is maximized when the information surface and the DVD focus FDVD match. The reflected beam from the information surface is narrowed by the detection lens 113 and enters the photodetector 411 via the cylindrical lens 116. Therefore, the reflected beam RBDVD of the DVD beam is focused on the center of the photodetector 411. The reflected light RBCD of the CD beam is incident on the entire photodetector 411 because the focal point FCD for CD is not on the information surface, and the whole becomes dim.

Next, the case of a two-layer DVD will be described. In the case of a dual-layer DVD, ENV / ASL is maximized when the first information surface or the second information surface matches the DVD focus FDVD. The figure shows a case where the first information surface and the DVD focus FDVD match. Note that AS1L / AS2L when the first information surface and the DVD focus FDVD coincide with each other and AS1L / AS2L when the second information surface and the DVD focus FDVD coincide with each other have substantially the same value. Things.

In the case of this two-layer DVD, the reflected beam RBDVD1 of the DVD beam from the first information surface is focused on the center of the photodetector 411. The DVD beam and the CD beam transmitted through the first information surface are both reflected on the second information surface to become reflected beams RBDVD2 and RBCD, respectively, and are incident on the entire photodetector 411. The reason for this is that the focal point FCD of the CD beam and the focal point FDVD of the DVD beam transmitted through the first information surface do not coincide with the information surface.

Since the reflectivity of the information surface of the single-layer DVD is higher than the reflectivity of the information surface of the double-layer DVD, the amount of light received inside the photodetector 411 in the case of the single-layer DVD (by the reflected beam RBDVD) Is higher than the amount of light received inside the photodetector 411 (by the reflected beam RBDVD1) in the case of a two-layer DVD. In the case of a two-layer DVD, the reflected beam RBDVD2 of the DVD beam from the second information surface is incident on the outside of the photodetector 411, and further the reflected beam of the CD beam from the first and second information surfaces. Since RBCD1 and RBCD2 are added, the amount of light received outside the photodetector 411 in the case of a two-layer DVD is larger than the amount of light received outside the photodetector 411 (by the reflected beam RBCD) in the case of a single-layer DVD. growing. Therefore, as described above, the value of AS1L / AS2L is larger for a single-layer DVD than for a double-layer DVD.

Further, the case of a CD will be described. In the case of a CD, ENV / ASL is maximized when the information surface and the focus FCD for CD match. Therefore, the reflected beam RBCD of the CD beam is focused on the center of the photodetector 411. The reflected light RBDVD of the DVD beam enters the entire photodetector 411 because the DVD focus FDVD is not on the information surface.

Since the intensity of the DVD focus FDVD is higher than the intensity of the CD focus FCD, the amount of light received (by the reflected beam RBDVD) inside the photodetector 411 for a single-layer DVD is equal to the photodetector for a CD. The light reception amount inside 411 (depending on the reflected beam RBCD of the CD beam) is larger. In the case of a CD, the reflected beam RBDVD of the DVD beam is incident on the outside of the photodetector 411. It is larger than the amount of light received on the outside (based on the reflected beam RBCD).

Therefore, as described above, the value of AS1L / AS2L is larger for a single-layer DVD than for a CD.
According to the experiment, the value of AS1L / AS2L of the single-layer DVD is about 1.5 times that of AS1L / AS2L in each of the double-layer DVD and CD. As described above, the level ENVp of the ENV signal in the state where ENV / ASL becomes the maximum value is, as described above, the value of the level in the single-layer DVD and the level of the level in each of the two-layer DVD and CD. Greater than value. In the case of a disk having a standard reflectance, the maximum value ASLmax of the ASL is substantially equal for a single-layer DVD, a double-layer DVD, and a CD regardless of the disk.

Hereinafter, a method for determining a single-layer DVD will be described.
The ENV / ASL is calculated while moving the focusing lens 170 in a direction perpendicular to the information surface of the disk, and AS1Lp, AS2Lp, ASLp, and ENVp at the timing when this value becomes the maximum value are stored. Further, the maximum value ASLmax of the ASL in the entire period in which the focusing lens 170 is moved is measured. From the above values, the value Y is calculated according to the following equation.
Y = (ENVp / ASLmax) × AS1Lp / AS2Lp

は As for the value of Y, the value of the single-layer DVD is much larger than the value of the double-layer DVD and CD. In experiments, the value for single-layer DVDs is about four times the value for double-layer DVDs and CDs. Therefore, the value of the single-layer DVD and the intermediate value F between the values of the double-layer DVD and CD are calculated in advance, and this is compared with Y to determine that the disc is a single-layer DVD. Can be determined. At this time, since the ASLmax is used, the value Y is not affected even if there is variation in the reflectance of the disk or the like.

In the fourth embodiment, the determination is made using the above-described value Y. However, for the above-described reason, the determination can be made using the value Y2 of the following equation.
Y2 = AS1Lp / AS2Lp

If the variation in the reflectance of the disk is small, it can be determined using the value Y3 of the following equation.
Y3 = ENVp × AS1Lp / AS2Lp

In the apparatus according to the fourth embodiment, a single-layer DVD, a double-layer DVD, and a CD can be reproduced. In this case, the single-layer DVD and the CD can be distinguished from each other by the value of Y described above. That is, it is possible to discriminate a thin disk from a thick substrate.

Hereinafter, a method for distinguishing a dual-layer DVD from a CD will be described.
The ENV / ASL is calculated while moving the focusing lens 170 in a direction perpendicular to the information surface of the disk, and the ASL value ASLp at the timing when this value becomes the maximum value is measured. Further, the maximum value ASLmax of the ASL in the entire period in which the focusing lens 170 is moved is measured. From the above values, the value Z is calculated according to the following equation.
Z = ASLp / ASLmax

The value of Z is larger in the case of the dual-layer DVD than in the case of the CD.
This is because, in the case of a two-layer DVD, when the focal point FDVD for DVD coincides with the information surface of the first layer, the light beam transmitted through the first layer and reflected by the second layer almost enters the photodetector 411. That's why. This is because the distance between the first layer and the second layer is as short as about 40 μm. The same applies when the focus FDVD for DVD matches the second layer.

{Circle around (4)} In the case of a CD, when the DVD focus FDVD coincides with the information surface, the light beam of the DVD focus FDVD is reflected on the information surface, and almost all of the light is incident on the photodetector 411. In this state, ASL becomes the maximum value. This is because the light quantity of the DVD focus FDVD is larger than that of the CD focus FCD. Further, in the case of a CD, when the focal point FCD for CD coincides with the information surface, the light beam of the focal point FDVD for DVD is reflected on the information surface and becomes stray light, and protrudes from the photodetector 411. This is because the distance between the focal point FCD for CD and the focal point FDVD for DVD is about 300 μm. Therefore, the ASL level is lower than when the focus FDVD for DVD matches the information surface.

According to experiments, the value of Z of the dual-layer DVD is about 1, and the value of CD is about 0.5.
Therefore, by calculating in advance the intermediate value G between the values of the two-layer DVD and the CD and comparing this with Z, the two-layer DVD and the CD can be distinguished.

In the case of a single-layer DVD, the light quantity of the DVD focus FDVD is larger than that of the CD focus FCD. Therefore, even if the reflected light of the CD focus FCD protrudes from the photodetector 411, the value of ASLp is hardly affected. Absent. Therefore, the value of Z is almost 1. In the above description of the fourth embodiment, the value of Z is used to distinguish between a two-layer DVD and a CD, but a single-layer DVD and a CD can also be distinguished. That is, a disk with a thin base material and a disk with a thick base material can be determined by the value of Z.

The operation of the microcomputer 447 in the above determination will be described with reference to the flowcharts of FIGS.

(4) The microcomputer 447 substitutes Lmax for the variable FODA (step S11). Then, the value of the variable FODA is set in the D / A converter 141 (step S12).

Thereby, the focusing lens 170 moves upward. Here, Lmax is a value at which the focus FCD for CD and the focus FDVD for DVD are located above the information surface of the disc. Next, in the operation after the point a, the variables AS1Lp, AS2Lp, ASLp, ENVp, ASLmax, and Qmax are cleared (step S13). Then, as an operation after the point b, a value obtained by subtracting S from the variable FODA is substituted for the variable FODA (step S14). The value of the variable FODA is set in the D / A converter 141 (step S15). Here, S is much smaller than Lmax and positive. Accordingly, the output value of the D / A converter 141 decreases, and the focusing lens 170 slightly moves downward through the adder 132 and the power amplifier circuit 133.

(4) In this state, the microcomputer 447 calculates ENV / ASL and substitutes it for the variable Q (step S16). Then, the microcomputer 447 compares the value of the variable Qmax with the value of the variable Q (step S17), and if the variable Qmax is small, substitutes the value of the variable Q into the variable Qmax (step S18). Further, the microcomputer 447 substitutes the value of AS2L for the variable AS2Lp, and similarly substitutes the value of AS1L for AS1Lp and the value of ENV for the variable ENVp (step S19). Next, the microcomputer 447 compares the value of the variable ASLmax with the value of the ASL (step S20), and if the value of the variable ASLmax is small, substitutes the value of the ASL for the variable ASLmax (step S21).

Next, when the value of the variable FODA is larger than Lmin (NO in the determination in step S22), the process returns to the point b. When the value of the variable FODA is smaller than Lmin (YES in the determination in step S22), the operation proceeds to the operation after the next point c. Lmin is a value at which the focus FCD for CD and the focus FDVD for DVD are located below the information surface of the disc.

動作 By the operation from the point a to the point c, the focal point FCD for CD and the focal point FDVD for DVD pass the information surface of the disk once. The processing after point c is shown in FIG.

The processing from point c to point d is almost the same as the processing from point b to point c described above, except that the value obtained by adding S to the variable FODA is assigned to the variable FODA (step S11a) and step S12. From step S16 to step S16, and the point that the process ends when the value of the variable FODA becomes larger than Lmax (YES in step S22a). By the operation from the point c to the point d, the focal point FCD for CD and the focal point FDVD for DVD pass the information surface of the disk once. Therefore, the focal point FCD for CD and the focal point FDVD for DVD pass twice through the information surface of the disk by the processing from point a to point d. As a result, the timing at which ENV / ASL becomes maximum can be accurately detected. Also, during the period from point b to point d, the microcomputer 447 outputs a sine wave to the adder 454 via the D / A converter 455, which outputs the sine wave via the phase compensation circuit 135 and the power amplifier circuit 136. 170 is added. Thereby, the focusing lens 170 vibrates in a direction orthogonal to the track. As a result, it is possible to prevent the focus from being constantly located between the tracks, so that the information recorded on the track is easily reproduced, and the accurate level of the ENV signal can be measured.

FIG. 16 shows a change in the position of the focusing lens 170 during discrimination of a disk by the above operation. In the figure, the horizontal axis indicates time, the vertical axis indicates the position of the lens, and the positive direction indicates that it is closer to the disk 100. Points a, c, and d shown in FIGS. 14 and 15 correspond to points a, c, and d in FIG. 16, respectively. At the point in time when the discrimination process has been completed, the focusing lens 170 is located above. When the disc is a DVD, the focusing control is operated by detecting the first zero cross of the FE signal while gradually lowering the focusing lens 170. In the case of a CD, the focusing control is performed by detecting the first zero cross of the FE signal while lowering the focusing lens 170 and then gradually raising it.

Therefore, when a DVD is loaded in the apparatus, a signal can be reproduced in a shorter time after disc discrimination processing than when a CD is loaded.

Next, setting of the amplification factor of the amplifier 453 based on the value of AS1Lp will be described. The setting of the amplification factor is performed to accurately detect the timing at which the focusing control is operated. First, the timing for operating the focusing control will be described with reference to FIG.

FIG. 17 shows the FE signal for a single-layer DVD. The horizontal axis indicates time. The focusing lens 170 is gradually lowered, and the focal point FDVD for DVD approaches the information surface. The FE signal becomes negative at first, becomes zero when the information surface and the focus coincide, and then becomes positive.

The timing for operating the focusing control is the time point f when the information surface and the focus coincide. Therefore, it is detected that the FE signal has become larger than the comparison level Lc. In order to reduce the delay in the detection timing, it is necessary to make the comparison level Lc closer to the zero level Lz. However, since the FE signal includes noise and the like, the FE signal cannot be set to a completely zero level.

Therefore, the comparison level Lc is not the zero level Lz. In FIG. 17, the timing at the time point f is the timing for operating the focus control. By the way, the amplitude of the FE signal decreases when the reflectivity of the information surface of the disk or the intensity of the beam 150 decreases. Even if the comparison level Lc is the same, if the amplitude of the FE signal decreases, the detection delay increases. In the worst case, the amplitude of the FE signal may not reach the comparison level Lc. The FE signal whose amplitude has decreased is shown by a dotted line in the figure. In this case, the timing for operating the focus control cannot be detected. Therefore, the focusing control cannot be operated.

The change in the reflectance of the information surface of the disc and the intensity of the light beam 150 result in a change in the level of the AS1Lp signal when the focus coincides with the information surface. That is, if the reflectance or the like of the information surface of the disk decreases, the level of the AS1Lp signal decreases in proportion thereto. Therefore, the amplification factor of the amplifier 453 is set according to the level of AS1Lp when the information surface and the focal point corresponding to the disk loaded in the apparatus, that is, the DVD focal point FDVD or the CD focal point FCD coincide. For example, even if there is a change in the reflectance of the information surface of the disc, an FE signal having a constant amplitude can be obtained. Accordingly, by doing so, the timing at which the focusing control is operated can be detected accurately and reliably without the decrease in the amplitude of the FE signal as shown by the dotted line in FIG.

Therefore, the amplitude of the FD signal in the standard state is set to H, and AS1Lp is set to J. The amplitude when the FD signal is reduced is assumed to be H / 2. In this case, since AS1Lp is proportional to the amplitude of the FE signal, AS1Lp is J / 2. The microcomputer 447 doubles the amplification factor of the amplifier 453 because AS1Lp is J / 2, which is 50% of the standard state. Then, the amplitude of the FE signal input to the A / D converter 140 becomes H, which is the same as the standard state. Therefore, the timing for operating the focusing control can be reliably detected.

In the fourth embodiment, the timing at which the value of ENV / ASL becomes maximum is the timing when the DVD focus (FDVD) coincides with the information surface in the case of a DVD (single-layer type). This is the timing when the focus FDVD for use coincides with one of the two information surfaces, and in the case of a CD, the timing when the focus FCD for CD matches the information surface. According to experiments, ENV / AS1L also exhibits characteristics similar to the value of ENV / ASL, and therefore, in the present invention, ENV / AS1L may be used instead of ENV / ASL. In the present invention, the ENV signal is detected from the AS signal. However, this may be detected from the AS1 signal, and similar characteristics can be obtained.

In Embodiment 4 described above, one photodetector 411 including five light receiving surfaces has been described. However, if the configuration of the optical system is changed, the photodetector 411 may be configured using two photodetectors. . FIG. 18 shows a block diagram using two photodetectors. The same blocks as those in FIG. 10 are denoted by the same reference numerals, and description thereof will be omitted. The points different from the block diagram of FIG. 10 are a photodetector 111, a half mirror 601, and a photodetector 602. The light detector 111, the half mirror 601, and the light detector 602 are mounted on the transfer table 104.

The photodetector 111 is a photodetector that is obtained by removing the light receiving surface E of the light detector 411 in FIG. 10 and including only the light receiving surfaces A, B, C, and D. The light detector 602 is a light detector in which the light receiving surfaces A, B, C, and D of the light detector 411 are removed and only the light receiving surface E is provided.

FIG. 19A is a schematic diagram of the photodetector 111, and FIG. 19B is a schematic diagram of the photodetector 602. Note that, in the photodetector 602 of FIG. 19B, the hatched portion is the light receiving surface. These photodetectors 111 and 602 are mounted such that the points P and Q, which are the centers of the photodetectors, respectively coincide with the optical axis of the incident light.

The light beam that has passed through the cylindrical lens 116 is split into two beams by the half mirror 601. One light beam enters the photodetector 111. The other light beam enters the photodetector 602. The light detector 602 is mounted at a position where the distance from the half mirror 601 to the light detector 602 is equal to the distance from the half mirror 601 to the light detector 111. Therefore, the input signals of the I / V converters 114, 115, 119, 120 and 450 are the same as in the case of the configuration shown in FIG. Therefore, the operation of the device is the same as the configuration in FIG.

As described above, according to the optical disk device of the fourth embodiment, the optical head having two focal points, one for reproducing a disk with a thick base material and the other for reproducing a disk with a thin base material, In the optical disk apparatus using the optical disk, the photodetector 411 detects the respective intensities of the reflected light at the central portion and the reflected light at the peripheral portion. And a CD having a large base material thickness.

{Circle around (4)} By using the amount of light received by the photodetector 411 when the ENV signal reaches the maximum value, the disc can be accurately determined.

Also, by using the amount of light received by the photodetector 411 when the value obtained by dividing the ENV signal by the level of the ASL signal becomes the maximum value, it is possible to accurately discriminate the disc 100 even if the reflectivity of the disc 100 varies. it can.

Also, the light receiving amount AS1Lp of the first light receiving region of the photodetector 411, the light receiving amount AS2Lp of the second light receiving region, and the amplitude value ENVp of the information signal are measured, and the ratio of (AS1Lp × ENVp) to AS2Lp is determined. By using this, the accuracy of disc identification can be improved.

The light receiving amount AS1Lp of the first light receiving region, the light receiving amount AS2Lp of the second light receiving region, the amplitude value ENVp of the information signal, and ASLmax of the light detector 411 are measured, and the ratio between AS1Lp × ENVp and AS2Lp × ASLmax is measured. By using the disk, it is possible to accurately determine the disk even if the reflectance of the disk varies.

Also, the same effect as described above can be obtained when the photodetector 411 in FIG. 10 is configured by the photodetector 111 and the photodetector 602 shown in FIG.

Further, according to the fourth embodiment, in an optical disc apparatus using an optical head having two focal points, one for reproducing a disk with a thick base material and the other for reproducing a disk with a thin base material, By detecting the intensity of the reflected light at the center and the intensity of the reflected light at the periphery by the photodetector 411, a disc having one information surface and a disc having two information surfaces are determined based on the ratio of the intensities. Can be determined.

{Circle around (4)} By using the amount of light received by the photodetector 411 when the ENV signal reaches the maximum value, the disc can be accurately determined.

Also, by using the amount of light received by the photodetector 411 when the value obtained by dividing the ENV signal by the level of the ASL signal is maximum, it is possible to accurately determine the disk even if the reflectance of the disk 100 varies. .

Also, the light receiving amount AS1Lp of the first light receiving region of the photodetector 411, the light receiving amount AS2Lp of the second light receiving region, and the amplitude value ENVp of the information signal are measured, and the ratio of AS1Lp × ENVp to AS2Lp is used. Thus, the accuracy of disc discrimination can be improved.

Further, the light receiving amount AS1Lp of the first light receiving region of the photodetector 411, the light receiving amount AS2lp of the second light receiving region, the amplitude value ENVp of the information signal, and ASLmax are measured, and AS1Lp × ENVp and AS2Lp × ASLmax are measured. Since the ratio is used, the disc can be accurately determined even if the reflectivity of the disc varies.

Note that the same effect as described above can be obtained also when the photodetector 411 in FIG. 10 is configured by the photodetector 111 and the photodetector 602 shown in FIG.

Further, according to the fourth embodiment, the optical head device having two focal points, one for reproducing a disk with a thick base material and the other for reproducing a disk with a thin base material, is mounted. Since the amount of received light ASLp when the focal point suitable for the disc 100 is in the vicinity of the information surface and the maximum value ASLmax of the amount of received light when the focal point is moved are measured, the ratio between ASLp and ASLmax is obtained. Based on the ratio, it is possible to discriminate between a disk having a large substrate thickness and a disk having a small substrate thickness.

Also, by using the amount of light received by the photodetector 411 when the value obtained by dividing the ENV signal by the level of the ASL signal is maximized, a suitable focus is located near the information surface even if the reflectance of the disc 100 varies. Can be accurately detected.

Further, according to the fourth embodiment, in an optical disc apparatus using an optical head having two focal points, one for reproducing a disk with a thick base material and the other for reproducing a disk with a thin base material, When it is detected from the output of the photodetector 411 that a suitable focal point for the loaded disc 100 is near the information surface, an out-of-focus detection signal in the focusing control means is amplified according to the value of the received light amount AS1Lp. Since the amplification factor of the amplifier 453 having a variable amplification factor is changed, the amplitude of the FE signal becomes constant even when the reflectance of the disk varies, so that the timing for operating the focusing control can be made accurate.

In addition, after changing the amplification factor of the amplifier 453, the focusing control is operated at the timing when the output signal of the amplifier 453 reaches a predetermined level. Therefore, the focusing control is operated at an incorrect timing due to noise or the like. There is no such thing.

Also, by using the amount of light received by the photodetector 411 when the value obtained by dividing the ENV signal by the level of the ASL signal is maximized, a suitable focus is located near the information surface even if the reflectance of the disc 100 varies. Can be detected at an accurate timing.

Further, according to the fourth embodiment, the two focal points, that is, the focal point for reproducing a disk with a thick base material and the focal point for reproducing a disk with a thin base material, each pass through the information surface twice. With such a configuration, the amount of reflected light from the disk 100 can be accurately detected.

Embodiment 5 FIG.
Next, a fifth embodiment of the present invention will be described.

FIG. 20 shows a block diagram of an optical disk device according to Embodiment 5 of the present invention. The same blocks as in the third embodiment are denoted by the same reference numerals, and description thereof is omitted. What differs from the third embodiment is a signal processing circuit 500 and a microcomputer 547.

The signal processing circuit 500 reproduces information recorded on the disc 100 from the output signal AS1 of the adder 148, converts the information into digital data, and sends the digital data to the microcomputer 547.
Note that the signal processing circuit 500 can reproduce information of a CD and a DVD. Switching of the operation is performed by a command from the microcomputer 547.

The operation of the device shown in FIG. 20 will be described with reference to the waveforms shown in FIGS. 21 (a) and 21 (b). The waveform in FIG. 21A shows the position of the focusing lens 170. The waveform in FIG. 21B shows the FE signal which is the output signal of the differential amplifier 117.

In FIG. 20, when the disc 100 is placed on the tray 149, the microcomputer 547 drives the motor 118 to attach the disc 100 to the rotating shaft 102 of the motor 101. Next, the transfer table 104 is moved to the inner periphery of the disk 100. Then, the microcomputer 547 rotates the motor 101. The rotation speed of the motor 101 is set to the rotation speed of the inner circumference of the CD. The microcomputer 547 sets a value in the D / A converter 141 and temporarily lowers the focusing lens 170, as shown at t210 in the waveform of FIG. And then gradually raise. At this time, the switches 131 and 134 are open. Here, the output signal of the D / A converter 141 is sent to the actuator 172 via the addition circuit 132 and the power amplifier 133, so that the level of the output signal of the D / A converter 141 depends on the position of the focusing lens 170. It corresponds to.

(4) While gradually raising the focusing lens 170, the switch 131 is closed at the timing when the ENV signal exceeds a predetermined level and the FE signal first crosses zero, thereby performing the focusing control. This is the timing of t211 of the waveform of FIG. As described in the third embodiment, when the disc 100 is a CD, the timing at which the focusing control is operated is the timing at which the CD focus FCD is located on the information surface of the disc. Therefore, focusing control is performed so that the focal point FCD for the CD is located on the information surface of the CD. Then, the microcomputer 547 closes the switch 134 to operate the tracking control. Further, the microcomputer 547 switches the signal processing circuit 500 to an operation state for reproducing the information of the CD. Therefore, the signal processing circuit 500 reproduces the information recorded on the disk 100 and sends it to the microcomputer 547. In FIGS. 21A and 21B, waveforms indicated by dotted lines are waveforms when the focusing control is not operated. That is, the waveform is as described in the third embodiment.

Further, the signal processing circuit 500 will be described with reference to FIGS. 21 (c) and 21 (d).
FIG. 21C is a block diagram of the signal processing circuit 500. The input terminal 601 is connected to the adder 148, and receives the AS1 signal. The output terminal 605 is connected to the microcomputer 547. The CD information reproducing circuit 602 is a circuit for reproducing information of a CD. The DVD information reproducing circuit 603 is a circuit for reproducing information of a DVD. The switch 606 switches the signal of the terminal a or the terminal b based on the level of the control terminal d and outputs the signal to the terminal c. The input terminal 604 is connected to the control terminal d of the switch 606.

FIG. 21D is a block diagram of the CD information reproducing circuit 602, and an AS1 signal is input to an input terminal 704. The output terminal 705 is connected to the switch 606. The high-pass filter 700 removes low frequency components. The comparator 701 outputs a high-level signal when the level of the input signal is higher than zero level, and outputs a low-level signal when the level of the input signal is lower than zero level. The periodic pattern detection circuit 706 detects a periodic pattern at the beginning of a frame. Here, the frame is a frame in the CD signal format.

The conversion circuit 702 converts the data into 8-bit data every time 17-bit data is input, and outputs the data. The reference timing for dividing the input signal data into 17-bit data is based on the output signal of the periodic pattern detection circuit 706. This conversion is performed according to a conversion table based on EFM (eight-to-fourteen modulation) which is a modulation method of the CD system. In EFM, 14-bit data out of 17 bits has information, and the possible values of the 14-bit data are limited to 256 values. Therefore, the conversion table converts 256 types of input data into corresponding 8-bit data. An output signal of the conversion circuit 702 is sent to an error correction circuit 703. The error correction circuit 703 performs error correction of the CD system.

Since the focus FCD for the CD is now located on the information surface of the CD, the data input to the conversion circuit 702 is one of the 256 types in the conversion table. Therefore, the input data is correctly converted. Therefore, the information recorded on the disc 100 is reproduced.

Next, the operation when the disc 100 is a DVD will be described. The timing at which the focusing control is activated is a timing at which the CD focus FCD is located on the information surface of the disc, even though the disc is a DVD. Therefore, focusing control is performed so that the focal point FCD for CD is located on the information surface. Then, the microcomputer 547 closes the switch 134 to operate the tracking control. Further, the microcomputer 547 switches the signal processing circuit 500 to an operation state for reproducing the information of the CD.

However, the modulation method of the CD system is different from the modulation method of the DVD. For this reason, the data input to the conversion circuit 702 in the signal processing circuit 500 is different from the 256 types of data in the conversion table. Therefore, conversion circuit 702 does not output data. Therefore, the information cannot be sent to the microcomputer 547 because the error correction circuit 703 does not operate.

(4) When the microcomputer 547 knows that no information has been sent from the signal processing circuit 500, it determines that the disk 100 is a DVD. Then, the switches 131 and 134 are opened to deactivate the focusing control and the tracking control. The following operation will be described with reference to the waveforms shown in FIGS. The waveform in FIG. 22A shows the position of the focusing lens 170. The waveform in FIG. 22B shows the FE signal which is the output signal of the differential amplifier 117.

(5) The microcomputer 547 sets the rotation speed of the motor 101 to the rotation speed of the inner circumference of the DVD as described above. Then, as shown at t310 in the waveform of FIG. 22A, a value is set in the D / A converter 141, and the focusing lens 170 is once brought closer to the disk 100. Thereafter, while the focusing lens 170 is gradually lowered, the switch 131 is closed at the timing when the FE signal first crosses zero, and the focusing control is operated.

タ イ ミ ン グ This is the timing of t311 in the waveform of FIG. As described in the third embodiment, when the disc 100 is a DVD, the timing at which the focusing control is operated is the timing at which the DVD focus FDVD is positioned on the information surface of the disc. Then, the microcomputer 547 closes the switch 134 to operate the tracking control. Further, the microcomputer 547 switches the signal processing circuit 500 to an operation state for reproducing information of the DVD. Therefore, the signal processing circuit 500 reproduces the information recorded on the disk 100 and sends it to the microcomputer 547. The waveform shown by the dotted line in FIG. 22 is a waveform obtained when the focusing control is not operated. That is, the waveform is as described in the third embodiment.

In the fifth embodiment, the microcomputer 547 starts operation assuming that the disk 100 is a CD first, but may start operation assuming that the disk 100 is a DVD first. In this case, the rotation speed of the motor 101 is set to the rotation speed of the inner circumference of the DVD. Then, after the focusing lens 170 is once raised, while gradually lowering, the focusing control and the tracking control are operated at the timing when the FE signal first crosses zero. The signal processing circuit 500 is set to an operation state for reproducing information of a DVD. If the information cannot be reproduced, the focusing control and the tracking control are made inoperative. Then, it is determined that the disk 100 is a CD, and the rotation speed of the motor 101 is set to the rotation speed of the inner circumference of the CD. The microcomputer 547 operates the focusing control at the timing when the ENV signal exceeds a predetermined level and the FE signal first crosses zero while gradually lowering the focusing lens 170 and then gradually raising the focusing lens 170. Activate control. The signal processing circuit 500 is set to an operation state for reproducing information of a CD.

As described above, according to the optical disk device of the fifth embodiment, the optical head having the two focal points, the focal point for reproducing a disk with a thick base material and the focal point for reproducing a disk with a thin base material, In the optical disc device using the method, even when the focusing control is operated using the inappropriate focus, the signal processing circuit 500 can detect that the focusing control is operated using the inappropriate focus. Therefore, the focusing control can be operated again with a suitable focus.

The present invention can be used as an optical disk device capable of reproducing a plurality of types of optical disks such as a CD and a DVD, and is particularly useful as an optical disk device for a computer, an audiovisual device, or the like.

FIG. 1 is a block diagram of an optical disc device according to a first embodiment of the present invention. The FE signal, AS1 signal, AS1L signal, ENV signal, and the position of the focal point F (FIGS. (A), (b), (c), (d), and (e), respectively) in the first embodiment are shown. Waveform diagram for explaining. In each of the DVD1, DVD2, CD, and CD-R (FIGS. (A), (b), (c), and (d), respectively), a disc for discriminating the disc according to the first embodiment is described. FIG. 4 is a waveform diagram of an ENV signal and an AS1L signal. FIG. 6 is a block diagram of an optical disc device according to a second embodiment of the present invention. FIG. 9 is a block diagram of an optical disc device when a period measurement circuit is used in the second embodiment. FIG. 9 is a block diagram of an optical disc device according to a third embodiment of the present invention. FIG. 9 is a schematic diagram of an optical system having two focal points according to the third embodiment. FIG. 13 is a waveform chart showing an FE signal and an ENV signal in each of DVD1, DVD2 and CD (FIGS. (A), (b) and (c), respectively) in the third embodiment. An ENV signal for each of DVD1, DVD2, CD, and CD-R (FIGS. (A), (b), (c), and (d), respectively) for explaining disc discrimination in the third embodiment. FIG. 4 is a waveform chart showing an AS1L signal. FIG. 13 is a block diagram of an optical disc device according to a fourth embodiment of the present invention. FIG. 14 is a schematic view of a photodetector 411 according to the fourth embodiment. 13 is a flowchart showing the operation of the device according to the fourth embodiment. Waveform diagram showing FE signal, ENV signal, AS1L signal, ASL signal, ENV / AS1 in each case of DVD1, DVD2, and CD (FIGS. (A), (b), and (c), respectively) in the fourth embodiment. . 15 is a flowchart showing the first half of the determination operation in the fourth embodiment. 19 is a flowchart showing the latter half of the determination operation in the fourth embodiment. FIG. 14 is a waveform diagram showing the movement of the focusing lens 170 according to the fourth embodiment for each of DVDs and CDs (FIGS. 7A and 7B, respectively). FIG. 19 is a waveform chart showing an FE signal for explaining the operation of the amplifier 453 according to the fourth embodiment. FIG. 14 is a block diagram of an optical disc device when two photodetectors are used in the fourth embodiment. FIG. 14 is a schematic diagram of two photodetectors according to the fourth embodiment. FIG. 13 is a block diagram of an optical disc device according to a fifth embodiment of the present invention. Waveform diagrams (FIGS. 3A and 3B) showing the position of the focusing lens 170 and the FE signal for explaining the fifth embodiment, and a circuit showing the signal processing circuit 500 and its CD information reproducing circuit. Block diagrams (Figures (c) and (d)). FIG. 14 is a waveform diagram showing the position of a focusing lens 170 and an FE signal for explaining the fifth embodiment ((a), (b)). FIG. 13 is a diagram for explaining a relationship between a value Z and a disk type and a determination method using the same in the third embodiment. In the fourth embodiment, when the disc 100 is a single-layer DVD, a double-layer DVD, or a CD, the positional relationship between the DVD focus and the CD focus and the information surface in a state where the ENV / ASL is maximized. FIG. 4A is a diagram illustrating a reflected beam ((b)) from the information surface of the disc 100 to a photodetector 411. FIG. 3 is a schematic diagram of a CD in a conventional example. FIG. 1 is a schematic diagram of a general two-layer DVD.

Explanation of reference numerals

REFERENCE SIGNS LIST 100 disc 101 motor 103 transfer motor 104 transfer table 105 laser 106 coupling lens 107 polarization beam splitter 108 quarter-wave plate 109 total reflection mirror 110 focusing lens 111 quadruple photodetector A, B, C, D light receiving surface 112 actuator 114, 115 I / V converter 117 Differential amplifier 118 Motor 119, 120 I / V converter 121, 122, 123, 124 Adder 125 Differential amplifier 126 Focusing lens 127 Actuator 128 Motor 129 Laser drive circuit 130 Phase compensation circuit 131 switch 132 adder 133 power amplifier 134 switch 135 phase compensation circuit 136 power amplifier 143 envelope detection circuit 147 microcomputer 148 adder 150 light beam 165 b Pass filters 142, 144, 140 A / D converter 149 Tray 160 Band pass filter 161 Comparator 172 Actuator 170 Focusing lens 171 Hologram 411 Five-part photodetector E Light receiving surface 447 Microcomputer 450 I / V converter 451 Low-pass filter 452, 461 A / D converter 453 Amplifier with variable amplification factor 454, 462 Adder 455 D / A converter 500 Signal processing circuit 500
547 Microcomputer 602 CD information reproduction circuit 603 DVD information reproduction circuit 606 Switch 707 High-pass filter 701 Comparator 706 Periodic pattern detection circuit 702 Conversion circuit 703 Error correction circuit

Claims (4)

An optical disk device including an optical system for a disk with a thin base material and an optical system for a disk with a thick base material,
Moving means for moving the focal point of a light beam for reproducing information from the information surface of the disc in a direction perpendicular to the information surface,
Light detection means for detecting the information reproduction signal amplitude based on the reflected light from the disc,
The maximum value of the information reproduction signal amplitude of the light detection means when the moving means is driven so that the focal point passes through the information surface is obtained, and the maximum value matches the loaded disc with the optical system used. An optical disc device comprising: a discriminating unit for discriminating whether a loaded disc is a disc having a thick base material or a disc having a thin base material, based on the fact that the size of the loaded disc is larger than that in a different case. An optical disk device including an optical system for a disk with a thin base material and an optical system for a disk with a thick base material,
Moving means for moving the focal point of a light beam for reproducing information from the information surface of the disc in a direction perpendicular to the information surface,
Light detection means for receiving light reflected from the disk,
Discriminating means for discriminating whether the loaded disc is a disc having a large base material thickness or a disc having a small base material thickness,
The moving means is driven so that the focal point passes through the information surface, and the maximum value AS1Lmax of the output value of the light detection means and the maximum value ENVmax of the information reproduction signal amplitude are obtained. The ratio between the ENVmax and AS1Lmax is determined by the loading. The discriminating means discriminates whether the loaded disc is a disc having a large base material thickness or a disc having a small base material thickness, based on the difference between the case where the loaded disc and the used optical system match and the case where the used optical system is different. An optical disk device characterized by comprising: The optical disk device according to claim 1, wherein
An optical disk device wherein an optical system for reproducing information recorded on a disk is an optical system for a disk having a thin base material. The optical disk device according to claim 1, wherein
An optical disk device, wherein, when the amount of light reflected from the disk exceeds an output value of the light detecting means, a moving means is controlled to reduce a moving speed of a focal point.

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