JPH11134780A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk device which accurately discriminates the kind of a disk (a CD or a DVD) and reduces the rising time till the reading of true disk information. SOLUTION: The device is provided with a driving means 8 which moves a focus 11 of light beams in an up and down direction with respect to the surface of a disk 12, a detecting means 15, which detects reflected light beams 19 of the disk 12 and a control means 24. Then, the means 24 moves the focus 11 at a prescribed speed, measures the time duration between the time, at which the beams 19 of the surface of the disk 12 are detected, and the time at which the beams 19 of the recording surface of the disk 12 are detected, and the kind of the disk 12 is discriminated by the measured time duration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a disk drive.

[0002]

2. Description of the Related Art Conventionally, this type of apparatus is disclosed in, for example,
No. 106617. According to this publication, a CD (Compact Disk) and a DVD (Di
It has been proposed that a single playback device play back a G.V.Gital Video Disk. Then, the focus of the light beam is adjusted to the recording surface of the disk, and the absolute value of the focus error signal due to the reflected light from the recording surface is measured. If the absolute value is larger than the threshold value, the disc is determined to be DVD, and if the absolute value is smaller, it is determined to be CD.

[0003]

However, in this device,
The focus error signal varies due to variations in the disk surface runout and rotational speed. Therefore, there is a first drawback that even if a CD is set, the disc is determined to be a DVD or the disc type is incorrectly determined. In order to solve this problem, the present inventor first irradiates a light beam with a CD laser to focus and reads disk information. If data is not correct, switches to a DVD laser and focuses and reads disk information. And As described above, there is the second disadvantage that the rise time until the true disk information is read is long.

Accordingly, the present invention provides a disk apparatus which can accurately determine the type of a disk (CD or DVD, etc.) and has a short rise time until true disk information is read in consideration of the conventional drawbacks. I do.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a driving means for moving a focal point of a light beam in a vertical direction with respect to a disk surface, and a detecting means for detecting light reflected from the disk. Control means, the control means moving the focal point at a predetermined speed, measuring the time interval from the time of detecting the reflected light of the disk surface to the time of detecting the reflected light of the recording surface of the disk, the time interval Is used to determine the type of disk.

[0006] Preferably, the control means measures a time interval between each point in time when reflected light from a plurality of recording surfaces formed on the disk is detected, and determines the type of the disk based on the time interval.

Preferably, the control means measures the number of times the reflected light from a plurality of recording surfaces formed on the disk changes, and determines the type of the disk based on the number of times.

Preferably, the control means compares a part or the sum of the reflected light amounts detected by the detecting means or a focus error signal with each threshold value, or compares the sum of the reflected light amounts with the threshold value. The determination is made by comparing the focus error signal with its threshold value.

Preferably, the threshold value on the surface of the disk is different from the threshold value on the recording surface formed on the disk.

[0010]

FIG. 1 is a block diagram showing a disk drive according to an embodiment of the present invention. FIG.
The irradiation means 1 includes, for example, a laser element 2 for DVD,
It comprises a half mirror 3, a collimator lens 4, a light beam splitter 5, a reflection mirror 6, a CD laser element 7, and the like. The DVD laser element 2 is, for example, 6
A laser beam of 50 nm is emitted, and the laser element for CD 7 emits a laser beam of 780 nm, for example.

The driving means 8 comprises an objective lens 9 and a focus drive circuit 10 and the like, and the focus drive circuit 10 comprises an electromagnetic coil and the like. By changing the voltage applied to the focus drive circuit 10 in this manner,
The objective lens 9 is configured to be held at an arbitrary position in the vertical direction. That is, the driving means 8 is provided with the focal point 11 of the light beam.
Can be moved vertically with respect to the surface of the disk 12.

The motor 13 is composed of, for example, a spindle motor, rotates the disk 12, and the motor drive circuit 14 supplies a predetermined voltage to the motor 13. The detecting means 15 includes a condenser lens 16, a light receiving element 17, and the like. The light beam 18 emitted by the irradiating means 1 is
The reflected light 19 is reflected by the reflection mirror 6, is reflected by the reflection mirror 6, is separated by the light beam splitter 5, is condensed by the condenser lens 16, and is incident on the light receiving element 17. As shown in FIG. 3, the surface of the light receiving element 17 is divided into, for example, six light receiving surfaces A, B, C, D, E, and F.

Each of the six light receiving surfaces is connected to a preamplifier 18a. The preamplifier 18a converts the light-receiving currents generated on the six light-receiving surfaces into respective voltages, and converts and outputs the combined voltages as follows. FE =
(A + C)-(B + D), SUM = A + B + C + D, T
E = EF, where FE is a focus error signal, SU
M is a sum signal, and TE is a tracking error signal. The RF (reproduced data) is obtained by converting the light-receiving currents generated on the four light-receiving surfaces A, B, C, and D into respective voltages and passing the sum through a filter (bandpass). different. As described above, the detection means 15
The reflected light 19 from 2 is detected.

The focus servo circuit 20 includes, for example, a subtraction circuit, a servo loop phase compensation circuit, a switch circuit, a drive circuit, and the like. The focus servo circuit 20 drives the objective lens 9 in the vertical direction in response to the input of the FE, thereby maintaining an appropriate distance between the objective lens 9 and the recording surface of the disk 12 with respect to the surface deflection of the disk. .

The tracking circuit 21 includes, for example, a phase compensation circuit, a switch circuit, a drive circuit, and the like. The tracking circuit 21 drives a tracking actuator (not shown) according to the input of the TE, controls the position of the objective lens 9 in the radial direction of the disk 12, and controls the track following of the light beam. As described above, the FE and the TE are input from the preamplifier unit 18a to the servo processing unit 22 including the focus servo circuit 20 and the tracking circuit 21. The focus servo circuit 20 outputs a focus control signal to the focus drive circuit 10.

The data processing unit 23 comprises, for example, an AD converter, a demodulator, a motor servo circuit and the like. The RF output from the preamplifier 18a is input to the data processor 23. The motor-on signal and the data processing setting signal output from the control unit 24 are input to the data processing unit 23.
An output terminal of the data processing unit 23 is connected to a host computer (both not shown) via an interface circuit, and another output terminal of the data processing unit 23 is connected to the motor drive circuit 14.

When the RF and the data processing setting signal are input to the data processing section 23, the data processing section 23 digitizes and demodulates the RF and outputs a reproduction signal to the host computer. The motor servo circuit employs, for example, the CLV method. In the case of a CD, the linear velocity of the disk 12 is 1.25 m.
/ S output a motor control signal.

The control means 24 comprises, for example, a CPU (Central Processing Unit) and is connected to a storage means ROM and RAM (both not shown). The ROM stores the program of the apparatus, and the RAM is used to store data when the RF is on standby. The host computer outputs a start signal for starting the apparatus to the control unit 24 via the data processing unit 23. The control unit 24 outputs a servo setting signal to the servo processing unit 22. The preamplifier section 18a is AD
The FE and SUM are output to the converter 25, and the digitized FE and SUM are input to the control means 24.

The laser control circuit 26 controls each output of the DVD laser element 2 and the CD laser element 7. When the control means 24 outputs a laser switching signal to the laser control circuit 26, the laser control circuit 26 outputs a predetermined voltage to the DVD laser element 2. When the laser switching signal is Lo, the control unit 24 outputs an ON signal to the laser control circuit 26, a predetermined voltage is applied to the CD laser element 7, and the CD
The laser element 7 starts emitting laser light. Due to the emission of the laser light, the light beam 18 is reflected by the disk 12, the reflected light 19 is received by the light receiving element 17, and the received light current is converted into a voltage by the preamplifier 18a, and is supplied as a monitor signal to the laser control circuit 26. Is entered. The laser control circuit 26 controls the output to the CD laser element 7 so that the monitor signal becomes constant. The disk device 27 is constituted by the above components.

Next, the relationship between the disk and the light beam in the disk device 27 will be described with reference to FIG. In FIG. 2A, the distance from the surface 28a of the CD (12a) as a disk to the recording surface 29a is 1.2 mm. FIG.
In (b), the distance from the surface 28b of the single-layer DVD (12b) to the recording surface 29b is 0.6 mm, and the distance from the recording surface 29b to the other surface 30b is 0.6 mm. In FIG. 2C, the distance from the surface 28c of the dual-layer DVD (12c) to the first recording surface 29c is 0.6 mm, and the distance from the first recording surface 29c to the second recording surface 29d is 50 μm, the distance from the second recording surface 29d to the other surface 30
The distance to c is 0.6 mm.

Next, a two-layer type DVD is
The operation when (12c) is mounted will be described with reference to FIGS. FIG. 4A is a diagram for explaining the voltage applied to the electromagnetic coil of the focus drive circuit 10, where the horizontal axis represents the elapsed time and the vertical axis represents the applied voltage. FIG. 4B is a waveform diagram of SUM (sum signal at four light receiving surfaces), and FIG.
FIG. 4D and FIG.
(E) is a waveform diagram of the timer output by the control means 24.

First, at time A1 in FIG. 4A, the host computer outputs a start signal. The start signal is input to the control unit 24 via the data processing unit 23. The control means 24 outputs the laser switching signal of Lo and the ON signal to the laser control circuit 26,
6 outputs the CD laser element 7, and the CD laser element 7 starts emitting laser light.

After a predetermined time has passed, A2 in FIG.
At this point, the control unit 24 outputs a motor-on signal to the data processing unit 23. The data processing unit 23 outputs a motor control signal to the motor drive circuit 14, and the motor 13 starts rotating. Next, the focus servo circuit 20 outputs a signal that decreases at a constant speed to the focus drive circuit 10. As a result, the objective lens 9 moves down to the lowest point A3.

At the lowest point A3, the search starts. That is, the reflected light 19 passes through the objective lens 9, is reflected by the reflection mirror 6, is separated by the light beam splitter 5, passes through the condenser lens 16, and enters the light receiving element 17. The light receiving current is converted into a voltage by the preamplifier 18a, and SUM and F
E is output. SUM and FE are input to the control means 24 via the AD converter 25 and are determined.

At the lowest point A3, the control means 24 outputs a control signal to the focus servo circuit 20, and the focus servo circuit 20 outputs a signal increasing at a constant speed to the focus drive circuit 10 according to the control signal. . As a result, the focal point 11 of the light beam rises at a constant speed.

Next, at time A4, the focal point 11 of the light beam
Reaches the surface 28c of the dual-layer DVD (12c) (see the broken line in FIG. 2C), the waveforms of SUM and FE change, and the control unit 24 measures the time point A4 (double-layer DVD).
The change of the reflected light 19 from the surface 28c of (12c) is measured).

Specifically, SUM shows a small convex waveform near the time point A4. FE shows a waveform that changes slightly near the time point A4. The control means 24 determines that the surface 28c is the period (A5) in which the value of SUM is equal to or more than the threshold value V1 and the time A4 when the value from the peak value of FE to the FE value reaches the threshold value V2 is the surface 28c judge. The control means 24 starts the built-in timer at the time point of A4 (see FIG. 4D).

Further, when the focal point 11 of the light beam is raised, the focal point 11 is moved to the double-layer DVD (12
The recording reaches the first recording surface 29c of c). At this time, SUM and F
Each waveform of E changes, and the control means 24 measures the time point A6 (measures the change of the reflected light 19 from the first recording surface 29c).

More specifically, the period (A7) in which the value of SUM is equal to or more than the threshold value V3, and the time when the FE reaches the threshold value V4 (= 0) after passing the peak value (zero cross point) The control means 24 determines that A6 is the first recording surface 29c. The control means 24 turns off the built-in timer at the time point A6 (see FIG. 4E).

In this way, the control means 24 measures the time interval T1 from the start of the timer to the stop of the timer. That is, the control means 24 measures the time interval T1 from the time point (A4) at which the reflected light 19 from the surface 28c changes to the time point (A6) at which the reflected light 19 from the first recording surface 29c changes. The control means 24 determines that the distance from the surface 28c to the first recording surface 29c is 0.6 mm by multiplying the speed at which the focal point 11 of the light beam moves by the time interval T1. As a result, the control means 24 determines that the type of the loaded disk is DVD.

As described above, since the change in SUM is small near the surface 28c, the threshold value V1 is reduced, and the change in SUM is large near the first recording surface 29c, so the threshold value V3 is increased. As described above, since the threshold value is set in accordance with the amount of change, the time of change can be measured more accurately. Also, for the FE, the threshold value V2 near the front surface 28c and the threshold value V4 near the first recording surface 29 are made different from each other to set a threshold value according to the amount of change, and Can be measured more accurately.

Further, the control means 24 compares the threshold value with the FE (focus error signal) based on the sum of the SUM based on the sum of the light receiving currents of the reflected light 19 and the FE (focus error signal). It is determined that it is the first recording surface 29c. As described above, since the determination is made based on both the SUM and FE signals, the accuracy is high. Note that the present invention is not limited to the above example, and a part or the sum (S
UM) or the focus error signal (FE) alone may determine the position of the front surface 28c or the first recording surface 29c.

When the focal point 11 is further raised, the focal point 11 reaches the second recording surface 29d at time A8. The control unit 24 determines that the period A8 when the SUM value is equal to or greater than the threshold value V3 and the FE has passed the peak value and the threshold value V4 (= 0) is reached is the second recording surface 29d. judge. That is, after measuring the first recording surface 29c, the control means 24 measures that the number of times the reflected light 19 from the recording surface changes is one (that is, the second recording surface 29d is present),
It is determined that the loaded disc is a dual-layer DVD (12c).

In the above description, if the control means 24 determines at time A8 that the number of times the reflected light 19 changes is 0 (ie, the second recording surface 29d does not exist), the control means 24 Discriminates that the disc is a single-layer DVD (12b).

As another means different from the above, at time A6 when the first recording surface 29c is measured, the control means 24 starts another timer and at time A8 when the second recording surface 29d is measured. , The control means 24 ends this timer. The control means 24 determines the time interval T2 from time A6 to time A8.
Is multiplied by the speed at which the focal point 11 moves to obtain a distance of 50 μm from the first recording surface 29c to the second recording surface 29d, and it is determined that the DVD is a two-layer DVD (12c).

After time A8, the control means 24 outputs to the servo processing section 22 servo coefficients (frequency characteristics of gain and phase in focus and tracking) corresponding to the dual-layer DVD (12c). At the same time, the control unit 24 outputs to the data processing unit 23 a setting signal necessary for decoder processing and CLV control. Further, the control means 24 outputs a laser switching signal to the laser control circuit 26, so that the output of the CD laser element 7 is stopped and the output of the DVD laser element 2 is started.

When the time reaches A9, the objective lens 9 moves down again.
It is measured that 1 coincides with the second recording surface 29d, and the focus jump (falls by 50 μm), and the focal point 11 coincides with the first recording surface 29c (time A11). When the time reaches A11, the focus servo circuit 20 controls the focus drive circuit 10 (focus-in).

The preamplifier section 18a has an RF (reproduced data)
Is output to the data processing unit 23, and the data processing unit 23
Is converted into a reproduction signal, and the reproduction signal is output to the host computer.

Next, the CD (12a) is stored in the disk device 27.
The operation when the device is mounted will be described with reference to FIGS. 5A is a diagram for explaining the voltage applied to the electromagnetic coil of the focus drive circuit 10, FIG. 5B is a waveform diagram of SUM, FIG. 5C is a waveform diagram of FE, and FIG. ) And FIG.
(E) is a waveform diagram of the timer output by the control means 24.

First, at the time point B1, the host computer outputs a start signal to the control means 24 via the data processing section 23, and the CD laser element 7 starts to emit light. B
At two points, the motor 13 starts rotating, the objective lens 9 descends, reaches the lowest point B3, and starts searching.

At the lowest point B3, the focal point 11 of the objective lens 9 rises at a constant speed. At the time of B4, SU
This is a period in which the value of M is equal to or more than the threshold value V1, and FE
The control means 24 determines that the time point B4 at which the value from the peak value to the FE value of the reference value reaches the threshold value V2 is the surface 28a. The control means 24 starts the timer at B4.

When the focal point 11 is further raised, at the time point B5, the period during which the SUM is equal to or more than the threshold value V3, and at the time point B5 when the FE has passed the peak and reached the threshold value V4 (= 0), Is the recording surface 29a, and the control means 24 determines that the timer is off.

As described above, the control means 24 measures the time interval T3 from the start of the timer to the stop of the timer. The control means 24 determines that the distance from the surface 28a to the recording surface 29a is 1.2 mm by multiplying the moving speed of the focal point 11 by the time interval T3. As a result, the control means 2
No. 4 determines that the type of the loaded disk is a CD.

[0044]

As described above, according to the present invention, the control means moves the focal point at a predetermined speed, and the control means measures the time when the reflected light changes on the disk surface. Then, the control means measures the time when the reflected light changes on the recording surface, measures the time interval between the two times, and calculates the distance from the disk surface to the recording surface based on the time interval. Since the interval at which the reflected light changes is measured in this manner, the type of the disc can be accurately determined with little variation due to the apparatus as in the related art.

Further, according to the present invention, when the focal point is moved in the vertical direction, the disc position is determined by measuring the position of the surface and the position of the recording surface. Rise time is fast.

Preferably, in the present invention, the control means measures a time interval between each time point at which reflected light from a plurality of recording surfaces formed on the disk is detected. Since the distance between the recording surfaces is calculated based on the time interval, the type of the disc can be accurately determined.

The present invention desirably measures the number of times the reflected light from a plurality of recording surfaces changes, and can easily determine the type of the disc based on the number of times.

In the present invention, preferably, the control means compares the sum signal based on the sum of the reflected light amounts with the threshold value thereof,
The focus error signal is compared with its threshold. As described above, since the change of the reflected light on the surface of the disk or the recording surface is measured by the two signals, the measurement accuracy is improved, and the disc determination becomes accurate. Further, the control means compares a part or the sum of the reflected light amount or the focus error signal with each threshold value. As described above, the change of the reflected light on the surface of the disk or the recording surface can be measured by one kind of signal.
Signal control becomes easy.

The amount of change in reflected light is different between the surface of the disk and the recording surface, but it is preferable that the threshold value at the surface of the disk be different from the threshold value on the recording surface. Can be measured more accurately.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a relationship between a light beam generated by the disk device and each disk.

FIG. 3 is a plan view of a light receiving element used in the disk device.

FIG. 4 is a diagram illustrating an operation when a two-layer DVD is mounted on the disk device.

FIG. 5 is a diagram illustrating an operation when a CD is mounted on the disk device.

[Description of Signs] 8 Driving means 11 Focus 12 Disc 15 Detection means 24 Control means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Satoshi Adachi 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd.

Claims (5)

[Claims] A driving means for moving a focal point of a light beam in a vertical direction with respect to a disk surface; a detecting means for detecting light reflected from the disk; and a control means. Moving at a speed, measuring the time interval from the point of detecting the reflected light of the disk surface to the point of detecting the reflected light of the recording surface of the disk, and determining the type of the disk based on the time interval. Characteristic disk device. 2. The method according to claim 1, wherein the control unit measures a time interval between each point in time when reflected light from a plurality of recording surfaces formed on the disc is detected, and determines the type of the disc based on the time interval. 2. The disk device according to claim 1, wherein: 3. The apparatus according to claim 1, wherein the control unit measures the number of times that the reflected light from a plurality of recording surfaces formed on the disk changes, and determines the type of the disk based on the number of times. Disk unit. 4. The control means compares a part or the sum of the reflected light amounts detected by the detecting means or a focus error signal with each threshold value, or compares the sum of the reflected light amounts with the threshold value. 2. The disk device according to claim 1, wherein the discrimination is made by comparing the focus error signal with its threshold value. 5. The disk device according to claim 4, wherein a threshold value on the surface of the disk is different from a threshold value on the recording surface formed on the disk.