JPH0935403A - Optical disc drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical disc drive to be loaded with various optical discs in which the type of optical disc can be discriminated highly accurately while reducing the weight and thickness. SOLUTION: The tracking servo in an optical pickup picks up a tracking error signal on an optical disc being loaded and an LPF circuit 41 takes out only the low band components therefrom. First and second comparators 42, 43 slice the low band components between high and low levels VH, VL and then a rotational period detection signal is produced from an OR circuit 44. A counter circuit 45 measures the duration of pulse and produces a control signal for determining the disc size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc device for mounting various types of optical discs.

[0002]

2. Description of the Related Art In recent years, for example, CD-ROM (Compact Disk-Read Only Memor) as a recording medium of an optical disk device
In y), various kinds of products with outer diameters of 12 cm and 8 cm are being supplied. If the outer diameter of the optical disc is different, it is necessary to change the gain of the control system such as the rotation control of the spindle motor that rotates the optical disc. Therefore, it is necessary to determine the type (outer diameter) of the optical disc to be mounted.

FIG. 9 is a block diagram of a conventional optical disk device. In an optical disk device 11 shown in FIG. 9, a spindle motor 13 is provided on a base 12, and an optical disk 15 (for example, an optical disk 15a having an outer diameter of 8 cm and an optical disk 15b having an outer diameter of 12 cm) is mounted on a mounting shaft 14 of the spindle motor 13. It is fixed by the clamper 16 which is attached and attracted by a magnet or the like.

An optical pickup 1 is mounted on the base 12.
A carriage 18 for mounting 7 is provided, and the carriage 1
8 is moved in the radial direction (C direction) of the optical disk 15 by the coarse movement motor 19. Actuators for performing tracking and focusing of the optical pickup 17 are mounted on the carriage 18, and the optical pickup 17 is slightly moved in the A direction (tracking) and the B direction (focusing).

Such an optical disk device 11 has an optical pickup 17 for obtaining optical information on the optical disk 15.
Focusing servo is performed so as to make a small distance in the B direction to keep the distance from the optical disk 15 constant. When the optical disk 15 is rotated by the spindle motor 13 in this state, a tracking error (TE) signal indicating the amount of positional deviation in the radial direction (A direction) from the optical information track is detected, and tracking is performed so that this TE signal becomes zero. Servo.

To move from the current track to another track, a coarse seek (macro seek) is performed by the coarse movement motor 19 and then the optical pickup 17 is finely seek (micro seek). And spindle motor 1
Reference numeral 3 is for detecting the rotational speed of the optical disk 15 from the optical information obtained from the optical disk 15 and controlling the rotational linear speed to be constant.

Therefore, in determining the type (outer diameter) of the optical disk 15, a magnet (or a coil) may be attached to the rotor side of the spindle motor 13 and a coil (or a magnet corresponding to the coil on the rotor side may be attached) to the stator side. It is known, for example, from Japanese Patent Application Laid-Open No. 1-98161 to detect the rotation cycle of the spindle motor 13 after the rotation by making a frequency generator by mounting the rotation frequency.

[0008]

However, providing the frequency generator as described above in order to discriminate the type (outer diameter) of the optical disk 15 to be mounted requires a space corresponding to the frequency generator. There is a problem that it is difficult due to dimensional restrictions amid thinning progress for mounting on a notebook personal computer.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an optical disk device for highly accurately determining the type of an optical disk while making it lightweight and thin.

[0010]

In order to solve the above-mentioned problems, according to a first aspect of the present invention, a motor for rotationally driving a mounted disk medium, an optical head for reading information recorded on the disk medium, and In a disk device comprising a transfer means for transferring an optical head in a radial direction of the disk medium and a servo means for controlling the optical head to follow a recording track on the disk medium, the disk device obtains from the servo means after stable rotation of the motor. Comparing means for comparing the servo error signal with a reference level and outputting it as a pulse signal; and a determining means for detecting the generation period of the pulse signal from the comparing means and determining the type of the mounted disk medium. An optical disk device provided is configured.

In the second aspect, the servo error signal obtained from the servo means according to the first aspect is a tracking error signal. According to a third aspect of the present invention, a control signal of the type of the optical disk medium from the determination means according to the first aspect is used to switch the control mode of the system control section that generalizes the entire apparatus.

According to another aspect of the present invention, there is provided a motor for rotationally driving the mounted disk medium, an optical head for reading information recorded on the disk medium, and a transfer means for transferring the optical head in a radial direction of the disk medium. And a servo device for controlling the optical head to follow the recording track on the disk medium, a servo error signal obtained from the servo device after stable rotation of the motor is compared with a reference level to obtain a pulse signal. First comparing means for outputting, second comparing means for comparing the RF signal obtained from the optical head with a reference level and outputting as a pulse signal, and the pulse signals from the first and second comparing means A transverse direction detection signal is generated, and the generation cycle of the transverse direction detection signal is detected to determine the type of the mounted disk medium. The optical disk apparatus is configured comprising a that discriminating means.

As described above, in the first or second aspect of the present invention,
Obtained by comparing the servo error signal such as a tracking error signal output from the servo means with the reference level when the optical head is controlled to follow the recording track on the mounted disk medium by the servo means. The discriminating means discriminates the type of the disk medium from the generation period of the pulse signal. As a result, the type of the disk medium can be discriminated without requiring a space for providing a dedicated frequency generator, and it is possible to achieve high-accuracy detection while achieving weight reduction and thinning.

According to the third aspect of the invention, the control mode of the system control section is switched by the discrimination signal from the discrimination means. As a result, it is possible to improve the accuracy of drive control of the motor or the like according to the type of disk medium. Further, in the invention of claim 4, the pulse signal obtained by comparing the servo error signal with the reference level by the first comparing means, and the second signal
The discriminating means discriminates the type of the disk medium by generating a transverse direction detection signal from the pulse signal obtained by comparing the RF signal with the reference level by the comparing means and detecting the generation period. As a result, the type of the disk medium can be detected with high accuracy without being affected by the variation in the eccentricity due to the mounting of the disk medium and the variation in the eccentricity due to the shaft tilt of the motor.

[0015]

FIG. 1 shows a configuration diagram of a first embodiment of the present invention. In the optical disk device 21 shown in FIG. 1, an optical disk 22 such as a CD-ROM or a magneto-optical disk, which is a disk medium, is rotatably mounted on a disk motor 23, and the optical disk 22 has an outer diameter (12 cm, 8 cm). Different types can be attached.

An optical pickup 2 which is an optical head
4 is provided so as to be movable in the radial direction of the optical disk 22 by a feed motor 25 which is a transfer means. The optical pickup 24 includes a laser diode 26 and a beam splitter 2.
7, an optical receiver (detector) 28, a reflecting mirror 29, and an objective lens 30.
Although not shown, actuators for finely moving the optical disk 22 in the horizontal direction and the vertical direction are respectively provided.

That is, the optical pickup 24 irradiates the optical disk 22 with the laser light emitted from the laser diode 26 through the beam splitter 27, the reflecting mirror 29, and the objective lens, and the reflected light from the optical disk 22 is the objective lens 30, Reflecting mirror 29, beam splitter 27
The light is received by the light receiving unit 28 via.

On the other hand, the circuit system is provided with a controller 31 which is a system control unit for controlling the entire apparatus, and the controller 31 includes a gain switching unit 32 for controlling the rotation of the disk motor 23. The controller 31 roughly controls the disk motor drive circuit 33, the focus servo circuit 34, the tracking servo circuit 35, the feed motor servo circuit 36, and the signal processing circuit 37.

The disc motor drive circuit 33 drives the disc motor 23 based on a control signal from the controller 31 so as to rotate the optical disc 22 at a predetermined rotation speed. The focus servo circuit 34 drives the actuator of the optical pickup 24 by a control signal from the controller 31 based on the detected focus error signal,
Focusing is performed by slightly moving the objective lens 30 in the direction of the optical disk 22. Tracking servo circuit 35
Drives the actuator according to a control signal from the controller 31 based on the detected tracking error (TE) signal, and minutely moves the objective lens 30 in the radial direction of the optical disc 22 to perform tracking.

The feed motor servo circuit 36 drives the feed motor 25 by a control signal from the controller 31 based on the detected position error signal, and the optical pickup 24.
To perform a coarse seek for moving between tracks. The signal processing circuit 37 processes the information reproduced by the optical pickup 24 under the control of the controller 31.

The TE signal from the tracking servo circuit 35 is sent to the disc discriminating circuit 38. The disc discriminating circuit 38 is equipped with a comparing means and discriminating means, which will be described later, and the type (outer diameter) of the optical disc 22 mounted. ) Is discriminated and the discrimination signal is sent to the gain switching unit 3 of the controller 31.
Send to 2. The controller 31 supplies a control signal obtained by switching the control gain of the disk motor 23 by the gain switching signal from the gain switching unit 32 based on this determination signal to the disk motor drive circuit 33, and the optical disk 22 at the rotation speed corresponding to the outer diameter. Is to rotate.

The disc of the above-mentioned optical disc device 21
If the medium is a magneto-optical disk, a magnetic head is not provided.
And is moved in the radial direction of the disk by the feed motor 25.
However, details are omitted. Therefore, in FIG. 2, the data of FIG.
The concrete circuit diagram of a disc discrimination circuit is shown. As shown in FIG.
In the disc discrimination circuit 38, the TE signal is LPF (low pass filter).
Filter circuit 41 and outputs only the low frequency component.
Is supplied to the non-inverting input terminal of the first comparator 42.
And the inverting input terminal of the second comparator 43
Supplied. To the inverting input terminal of the first comparator 42
Is the voltage V as the first slice level _HIs applied
The first slice level of the low frequency component from the LPF circuit 41.
Signal of a level above this level is detected, and its pulse signal is O
It is output to the R circuit 44.

Further, the voltage V _L as the second slice level is applied to the non-inverting input terminal of the second comparator 43 so that the low-frequency component from the LPF circuit 41 has a level equal to or lower than the second slice level. A signal is detected and the pulse signal is output to the OR circuit 44.

The OR circuit 44 outputs the output signals from the first and second comparators 42 and 43 in the input order, and outputs the rotation cycle detection signal to the counter circuit 45. The counter circuit 45 counts the interval of the input pulse signal and outputs it as a discrimination signal of the type (outer diameter) of the optical disk 22 according to the count. The LPF circuit 4
1, first and second comparators 42, 43 and OR
The circuit 44 constitutes a comparing means, and the counter circuit 45 constitutes a discriminating means.

Here, FIG. 3 shows a graph for explaining the principle of disc discrimination. FIG. 3 shows the relationship between the rotation speed of the motor (disk motor) 23 and the rising time. Generally, the rotation speed w of t seconds after applying the voltage V to the motor (t) is, w (t) = (V / K) · (1-exp (-t / τ m)) = (V / K ) - is represented by (1-exp (-t · K 2 / J · R)). In this case, K is a motor constant, τ _m is a mechanical time constant, J is inertia, and R is a motor coil resistance value.

Now, when the size (outer diameter) of the optical disk 22 is different, the inertia changes, which changes the mechanical time constant τ _m . This time constant τ _m is shown in FIG.
That is, when the outer diameter of the optical disk 22 is, for example, 12 cm, the time constant τ _m becomes large, which reduces the rising gradient of the motor (disk motor 23). Further, when the outer diameter of the optical disc 22 is, for example, 8 cm, the time constant τ _m becomes small and the motor rising gradient becomes large.

Therefore, when the above motor start-up changes, TE
The signal is generated, and the detection pulse generation cycle becomes longer in the case of the 12 cm optical disk 22.
In the case of 2, the detection pulse generation period becomes short, and the type (outer diameter) of the optical disk 22 can be discriminated.

Therefore, FIG. 4 shows a waveform diagram of the disk medium of FIG. In FIG. 4, the TE signal input to the LPF circuit 41 is a signal that is frequency-modulated as shown in FIG. 4A because the eccentric component of the optical disk 22 mounted inevitably appears. As shown in FIG. 4B, only the low frequency component of the TE signal is extracted by the LPF circuit 41 and is input to the first and second comparators 42 and 43.
The first comparator 42 outputs an "H" level pulse signal when the TE signal (low frequency component) exceeds the slice level V _H as shown in FIG. 4C. Also, the second
The comparator 43 outputs a pulse signal of "H" level when the TE signal (low frequency component) exceeds the slice level V _L as shown in FIG. 4 (D).

The first and second comparators 42 and 4
The pulse signal output from the circuit 3 is input to the OR circuit 44, and the pulse signal corresponding thereto is sequentially output from the OR circuit 44 to the counter circuit 45 as a rotation cycle detection signal as shown in FIG. 4 (E). The counter circuit 45 is the OR circuit 44.
The rotation speed of the optical disk 22 can be determined by measuring the time T ₁ between the rising (or falling) of the rotation cycle detection signal from the optical disc 22 and whether or not the set time is exceeded. Alternatively, the determination signal is output as an “L” signal. For example, if the pulse interval T ₁ is shorter than the set time, it is determined to be the 8 cm optical disc 22, and if it is longer than the set time, the 12 cm optical disc 22 is determined.

The discrimination signal from the counter circuit 45 is shown in FIG.
As described above, the gain of the control signal that is output to the gain switching unit 32, and the controller 31 switches the control mode accordingly and is sent to the disc motor drive circuit 33 is output according to the type (outer diameter) of the optical disc 22. To do. As a result, the accuracy of motor drive control can be improved.

As described above, since the type (outer diameter) of the loaded optical disk 22 can be discriminated from the TE signal, it is not necessary to provide a rotation cycle detecting means such as a dedicated frequency generator, and the corresponding portion can be used. No space is required and the weight of the device can be reduced. In particular, the optical disc 22
In determining the type (outer diameter) of the frequency generator (F
Since the FG signal from G) is not required, it is possible to deal with the case where the FG is unnecessary when the motor control signal is generated from the reproduction clock of the optical disk 22 to drive and control.

Further, since the number of parts is reduced, high reliability can be realized. Further, since the disk can be detected with low current consumption, high efficiency and long life can be realized. Further, since the startup sequence of the disk motor 23 is simplified, the motor startup time can be shortened and the performance can be improved.

Next, FIG. 5 shows a circuit diagram of essential parts of a second embodiment of the present invention. FIG. 5 is another circuit diagram of the disk determination circuit 38 of FIG. 1, in which the TE signal from the tracking servo circuit 35 is input to the non-inverting input terminal of the comparator 51, and the TE signal is input to the inverting input terminal of the comparator 51. The slice level VR is applied. The output of the comparator 51 is used as a track cross signal for the first counter circuit 5
2, and the output of the first counter circuit 52 is input to the second counter circuit 53 as a rotation cycle detection signal. Then, the determination signal is output from the second counter circuit 53. The comparator 51 and the first counter circuit 52 form a comparing unit, and the second counter circuit 53 forms a determining unit.

Therefore, FIG. 6 shows a waveform diagram for disc discrimination of FIG. 5 to explain the operation. In FIG. 6, the comparator 51 outputs a high-level pulse signal when the input TE signal (FIG. 6A) from the tracking servo circuit 35 exceeds the slice level VR. This output pulse signal Is input to the first counter circuit 52 as a track cross signal indicating that the data has crossed the recording track (FIG. 6 (B)). In the first counter circuit 52, the polarity reversal of the input track cross signal occurs at time t.
The second high-level pulse signal is output when the range of ₀ is exceeded.
To the counter circuit 53.

The pulse signal extracted by the first counter circuit 51 from this track cross signal is the disk motor 2
3 rotation period detection signal, and the second counter circuit 53
At this time, the time between the rising (or falling) of the pulse signal of the rotation cycle detection signal is measured, and the determination signal for determining the type (outer diameter) of the optical disk 22 is the controller 31 (gain switching unit 32) as described above. Is output to. As a result, the rotation cycle of the optical disk 22 can be detected, the rotation speed can be obtained, and the disk size can be detected, and the same effect as the first embodiment can be obtained.

Next, FIG. 7 shows a block diagram of essential parts of a third embodiment of the present invention. FIG. 7 is another circuit diagram of the disk discriminating circuit 38 of FIG. 1, in which the non-inverting input terminal of the first comparator 61 has a T from the tracking servo circuit 35.
The E signal is input, and the voltage VR ₁ as the first slice level is applied to the inverting input terminal. On the other hand, although not shown in FIG. 1, the disk motor 23 is provided with a frequency generator, and R when the rotation control is performed by being input to the controller 31 via the disk motor drive circuit 33.
The F signal is the second comparator 6 of the disc discriminating circuit 38.
2 is input to the non-inverting input terminal. A voltage of slice level VR ₂ is applied to the inverting input terminal of the second comparator 62.

The output of the first comparator 61 is input to the clock input terminal of the D flip-flop 63 as a track cross signal, and the output of the second comparator 62 is R.
The F reflection signal is input to the data input terminal of the D flip-flop 63. D flip-flop 63
The signal output from the output terminal Q of is output to the counter circuit 64 as a transverse direction detection signal, and the determination signal is output from the counter circuit 64 to the controller 31 (gain switching unit 32).

The operation will now be described with reference to FIG. 8 which shows a waveform diagram for disc discrimination in FIG. In FIG. 8, the first comparator 61 inputs the TE signal (FIG. 8A) from the tracking servo circuit 35 to the slice level V
The track cross signal (FIG. 8B) detected at R ₁ is supplied to the D flip-flop 63 as a clock signal.

On the other hand, the second comparator 62 supplies the RF reflection signal obtained by detecting the input RF signal (FIG. 8C) at the slice level VR ₂ to the D flip-flop 63 as a data signal. That is, when the laser beam from the optical pickup 24 crosses over the track of the optical disc 22 (corresponding to the white circle of the TE signal in FIG. 8A), the amount of return light from the optical disc 22 is large, so that the amplitude of the RF signal is large. Therefore, when crossing between tracks (corresponding to the black circle of the TE signal in FIG. 8A), the amount of return light from the optical disk 22 is small and RF
The signal amplitude decreases.

When this RF signal exceeds the slice level VR ₂ in the second comparator 62, the "H" level, V
When outputs a "L" level when below the R _2, when the quantity of return light much RF amplitude is large "L"
When the amount of returned light is small and the RF amplitude is small, an RF reflection signal which becomes a "H" level signal is obtained.

Further, the D flip-flop 63 outputs the value of the RF reflection signal at the rising edge of the track cross signal from the output terminal Q to the counter circuit 64 as a transverse direction detection signal. That is, an "L" level signal is output when the laser beam traverses a track in a predetermined direction (for example, an inner circumferential direction of the disk motor 23), and an "H" level signal is output when the laser beam traverses in the opposite direction. The cross direction detection signal shown in FIG. 8E is output and input to the counter circuit 64.

The counter circuit 64 can detect the rotation cycle of the optical disk 22 as described above by measuring the time between the rising edges (or falling edges) of the input transverse direction detection signal, and thereby the optical disk 22. The rotation speed of 22 is obtained to detect the disk size.

In the third embodiment, since the disc is discriminated by the transverse direction detection signal, the influence of the variation of the eccentricity due to the mounting of the optical disc 22 and the variation of the eccentricity due to the misalignment (axis tilt) of the disc motor 23, etc. It is generated without receiving it, and the disc size can be detected with higher accuracy.

[0044]

As described above, according to the first or second aspect of the present invention, the tracking output from the servo means when the servo control of the optical head follows the recording track on the mounted disk medium is performed. The discriminator discriminates the type of the disk medium from the pulse signal generation period obtained by comparing the servo error signal such as an error signal with the reference level by the comparator, thereby requiring a space for providing a dedicated frequency generator. Without discriminating the type of the disk medium, it is possible to achieve high-accuracy detection while achieving weight reduction and thinning.

According to the third aspect of the present invention, the precision of the drive control of the motor or the like according to the type of the disk medium is improved by switching the control mode of the system control unit by the discrimination signal from the discrimination means. You can further,
According to the invention of claim 4, the pulse signal obtained by comparing the servo error signal with the reference level by the first comparing means;
When the disc medium is loaded, the discriminating unit discriminates the type of the disc medium by generating a transverse direction detection signal from the pulse signal obtained by comparing the RF signal with the reference level by the comparing unit and detecting the generation period. It is possible to detect the type of the disk medium with high accuracy without being affected by the variation of the eccentricity and the variation of the eccentricity due to the shaft tilt of the motor.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a specific circuit diagram of the disc discriminating circuit of FIG.

FIG. 3 is a diagram for explaining the principle of disc discrimination.

FIG. 4 is a waveform diagram for disc discrimination of FIG.

FIG. 5 is a circuit diagram of an essential part of a second embodiment of the present invention.

FIG. 6 is a waveform diagram for disc discrimination of FIG.

FIG. 7 is a circuit diagram of an essential part of a third embodiment of the present invention.

FIG. 8 is a waveform diagram for disc discrimination of FIG. 7.

FIG. 9 is a configuration diagram of a conventional optical disc device.

[Explanation of symbols]

 21 optical disk device 22 optical disk 23 disk motor 24 optical pickup 25 feed motor 31 controller 32 gain switching section 33 disk motor drive circuit 34 focus servo circuit 35 tracking servo circuit 36 feed motor servo circuit 37 signal processing circuit 38 disk discrimination circuit

Claims (4)

[Claims] 1. A motor for rotationally driving a mounted disk medium, an optical head for reading information recorded on the disk medium, and a transfer means for transferring the optical head in a radial direction of the disk medium, In a disk device comprising a servo means for controlling the optical head to follow a recording track on a disk medium, a servo error signal obtained from the servo means after stable rotation of the motor is compared with a reference level and output as a pulse signal. An optical disc apparatus comprising: a discriminating unit that discriminates the type of the mounted disc medium by detecting a generation period of the pulse signal from the comparing unit. 2. An optical disk device, wherein the servo error signal obtained from the servo means according to claim 1 is a tracking error signal. 3. An optical disc apparatus, wherein a control mode of a system control section for generalizing the entire apparatus is switched by a discriminating signal of the type of the optical disc medium from the discriminating means according to claim 1. 4. A motor for rotationally driving the mounted disk medium, an optical head for reading information recorded on the disk medium, a transfer means for transferring the optical head in a radial direction of the disk medium, A disk device comprising a servo means for controlling the optical head to follow a recording track on a disk medium, wherein a servo error signal obtained from the servo means after stable rotation of the motor is compared with a reference level and is output as a pulse signal. 1, a second comparing means for comparing the RF signal obtained from the optical head with a reference level and outputting it as a pulse signal, and a transverse direction from the pulse signals from the first and second comparing means. A discriminating means for discriminating the type of the mounted disk medium by generating a detection signal and detecting the generation cycle of the transverse direction detection signal. An optical disk device comprising: a stage.